1
577 difficult problem. The maximum number is put under guardianship, but many respectable working-class people have been driven by the trade depression to seek relief in respect of a defective child, who would otherwise not have sought help. A proportion of defectives are unsuited for boarding-out-being easily led into crime, inebriety, prostitution, &c.-- but these should be given a trial, for under proper guardianship good habits may be acquired in youth. The higher-grade defective appreciates freedom, but guardians must be carefully selected, especially with regard to the sexual risk in the case of young females. In relation to the selection of guardians, Dr. Gibson reports that he has formed a very favourable idea of the sense of responsibility of, and care exercised by,’the average guardian, and urges that something be done to prevent the gradual decrease now apparent in the numbers of those willing to preserve the successful Scottish method of dealing with the insane poor. THE CERCARIAL FAUNA OF INDIA. THE elucitation ot the ine-nistories ot the ctlgenetlc trematodes, since the discovery of the life-cycle of Fasciola hepatica by Thomas in 1881, has always exercised a fascination for medical zoologists ; and the most recent contribution is in the form of an illustrated supplementary issue of the Indian Journal of Jledical Research, entirely occupied by an article by Major R. B. Seymour Sewell, I.M.S., entitled " Cercariee Indicae." The works of Sonsino and Looss (1896) were directed primarily to the eluci- dation of the life-cycle in Egypt of Schistosoma AcBMMoMMMt, the most noxious of all trematodes affecting man; during their researches they dis- covered and described numerous cercariae or larval trematodes in the fresh-water molluscs they dis- sected ; but, failing to trace them to their mature or parental forms, they were led to allocate them generic rank, to which descriptive specific names were attached. Ltihe (1909), in the course of similar researches on the cercariae of fresh-water snails in Germany, drew up a provisional classifi- cation of these cercarise on a morphological basis. The next important advance was the determina- tion in 1914 of the cercarial stage of Schistosoma japonicum by Miyairi, Suzuki, and Ogata, a discovery which was almost immediately confirmed and ex- panded by Leiper and Atkinson and finally completed by the former during his studies in Egypt, whereby the existence of two species of schistosomes infesting man in that country was established, and the life- histories traced through two different species of intermediary molluscan hosts and back to the definitive host again. The mainspring of this work was the differentiation and recognition of the furcocercous or fork-tailed cercarise as the larval stages of the Schisto- somidee from among the multitudinous cercarise inhabiting fresh-water molluscs. These researches imparted a fresh stimulus to the whole subject, and led to the work of Cawston in South Africa and the careful and intricate morphological studies of Faust on the cercariae of that country, as well as those of North America, a subject upon which Cort has also considerably expanded our knowledge. The dangers arising from the possible introduction of schistosomiasis into India from troops returning to that country who had become infected during their term of service in Egypt led to the study of this subject being undertaken by Kemp and Gravely, of the zoological survey of India. They found there, as had the several workers already mentioned in their respective areas, that they had entered upon a vast and hitherto unexplored field of zoological research, in which new forms of cercariae were continually presenting themselves. This subject has now been taken up by Major Sewell, the writer of the absorbing article under notice. One of his first discoveries was that of a fork-tailed cercaria in Indoplanorbis exustus and Limincea acuminata corresponding exactly to the description given by Cort for Schistosoma japonicum, though the mature form of this parasite is not known to occur in India. Still further researches have led to the production of this important work, in which are described and figured 57 cercarise of the fresh-water snail fauna of India, wherein a definite system of classification is based upon their outstanding morphological features, but no attempt has been made to allocate generic or specific rank to hitherto undescribed forms. On the other hand, this worker relies for his identification upon their tabulation with definite numerals, being rightly adverse to the bestowal of specific names upon larval forms. Such a study is beset with many difficulties, by no means the least being the uncer- tainty whether all cercarise can be separated upon an anatomical basis. Though the vast majority of known cercariee can be assigned to groups or sub- groups, we have no direct evidence that these groups necessarily correspond to various genera or sub- genera of the scheme of classification adopted for the adult trematodes. The majority of the fresh-water gastropods of India were found to harbour various cercarise, and the species found most frequently infected and apparently capable of acting as primary host to a large number of trematode species are Melanoides tuberculatus with 17 forms, and Indo- planorbis exustus with 15. The number in which the complete life-history is worked out is extremely small, and consequently the known adult forms are few. This is hardly to be wondered at considering the intricacy of the problem. The possible definitive hosts in any particular case may be birds, reptiles, mammals, batiachians, or fish, all of which are parasitised by trematodes. Many of these hosts are migratory, and may be infected during a short sojourn in India, so that it may be con- fidently predicted that many years will elapse before this subject is finally elucidated. As it is, helmin- thologists will be led to concentrate more upon life- histories than upon morphological features of the adult forms. This is a field which as yet has hardly been touched. Surveys of the cercarial fauna on the same lines as set forth in this monograph should be undertaken in all parts of the world, and their results compared. The immensity of the field may be gauged when one realises that Major Sewell has as yet derived his material from a comparatively small part of India. A critical survey of this important work will rest with the systematic zoologist, but of the permanent value of such a contribution to medical zoology there can be no doubt. ____ THE FUTURE OF THE TUBERCULOSIS COLONY. Two reports have just appeared synchronously, and as they represent different and, in some respects, opposite views, they give each other perspective and together form a useful contribution to the vexed problem of the tuberculosis colony. The first report! deals with the Papworth Hall Colony, which has recently enlarged its sphere of activities by the addition of 28 new cottages designed for patients and their families. When they are completed the total number of houses for ex-patients will be 50. The average number of patients in residence during the year under review was 168, reaching 175 in December. In 1921, 273 patients were admitted, and it will thus be seen that the number of patients who yearly leave the institution for some reason or other is considerable. This does not, however, necessarily reflect on the management of the colony, for there must be many undesirables of the tip-and-run stamp and others to whom the colony idea is distasteful, or for whom the sponsors of the colony have no taste. The majority of the patients were sanatorium failures, and some now earning their living in the colony had been drifting from one institution to another for years. With one or two possible exceptions, no early cases were admitted in 1921, the overwhelming majority being represented by patients with advanced disease. The report 1 The Cambridgeshire Tuberculosis Colony. Report of the Executive Committee for 1921. Printed by Papworth Industries. Pp. 34

THE CERCARIAL FAUNA OF INDIA

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difficult problem. The maximum number is put underguardianship, but many respectable working-classpeople have been driven by the trade depression toseek relief in respect of a defective child, who wouldotherwise not have sought help. A proportion ofdefectives are unsuited for boarding-out-beingeasily led into crime, inebriety, prostitution, &c.--but these should be given a trial, for under properguardianship good habits may be acquired in youth.The higher-grade defective appreciates freedom, butguardians must be carefully selected, especially withregard to the sexual risk in the case of young females.In relation to the selection of guardians, Dr. Gibsonreports that he has formed a very favourable idea ofthe sense of responsibility of, and care exercised by,’theaverage guardian, and urges that something be doneto prevent the gradual decrease now apparent in thenumbers of those willing to preserve the successfulScottish method of dealing with the insane poor.

THE CERCARIAL FAUNA OF INDIA.

THE elucitation ot the ine-nistories ot the ctlgenetlctrematodes, since the discovery of the life-cycle ofFasciola hepatica by Thomas in 1881, has alwaysexercised a fascination for medical zoologists ; andthe most recent contribution is in the form of anillustrated supplementary issue of the Indian Journalof Jledical Research, entirely occupied by an articleby Major R. B. Seymour Sewell, I.M.S., entitled" Cercariee Indicae." The works of Sonsino andLooss (1896) were directed primarily to the eluci-dation of the life-cycle in Egypt of SchistosomaAcBMMoMMMt, the most noxious of all trematodesaffecting man; during their researches they dis-covered and described numerous cercariae or larvaltrematodes in the fresh-water molluscs they dis-sected ; but, failing to trace them to their matureor parental forms, they were led to allocate themgeneric rank, to which descriptive specific nameswere attached. Ltihe (1909), in the course ofsimilar researches on the cercariae of fresh-watersnails in Germany, drew up a provisional classifi-cation of these cercarise on a morphological basis.The next important advance was the determina-tion in 1914 of the cercarial stage of Schistosomajaponicum by Miyairi, Suzuki, and Ogata, a discoverywhich was almost immediately confirmed and ex-

panded by Leiper and Atkinson and finally completedby the former during his studies in Egypt, wherebythe existence of two species of schistosomes infestingman in that country was established, and the life-histories traced through two different species ofintermediary molluscan hosts and back to the definitivehost again. The mainspring of this work was thedifferentiation and recognition of the furcocercous orfork-tailed cercarise as the larval stages of the Schisto-somidee from among the multitudinous cercariseinhabiting fresh-water molluscs. These researchesimparted a fresh stimulus to the whole subject, andled to the work of Cawston in South Africa and thecareful and intricate morphological studies of Fauston the cercariae of that country, as well as those ofNorth America, a subject upon which Cort has alsoconsiderably expanded our knowledge.The dangers arising from the possible introduction

of schistosomiasis into India from troops returning tothat country who had become infected during theirterm of service in Egypt led to the study of thissubject being undertaken by Kemp and Gravely, ofthe zoological survey of India. They found there,as had the several workers already mentioned in theirrespective areas, that they had entered upon a

vast and hitherto unexplored field of zoologicalresearch, in which new forms of cercariae were

continually presenting themselves. This subject hasnow been taken up by Major Sewell, the writerof the absorbing article under notice. One ofhis first discoveries was that of a fork-tailed cercariain Indoplanorbis exustus and Limincea acuminatacorresponding exactly to the description given byCort for Schistosoma japonicum, though the mature

form of this parasite is not known to occur in India.Still further researches have led to the production ofthis important work, in which are described andfigured 57 cercarise of the fresh-water snail fauna ofIndia, wherein a definite system of classification isbased upon their outstanding morphological features,but no attempt has been made to allocate generic orspecific rank to hitherto undescribed forms. On theother hand, this worker relies for his identificationupon their tabulation with definite numerals, beingrightly adverse to the bestowal of specific names uponlarval forms. Such a study is beset with manydifficulties, by no means the least being the uncer-tainty whether all cercarise can be separated upon ananatomical basis. Though the vast majority ofknown cercariee can be assigned to groups or sub-groups, we have no direct evidence that these groupsnecessarily correspond to various genera or sub-genera of the scheme of classification adopted for theadult trematodes. The majority of the fresh-watergastropods of India were found to harbour variouscercarise, and the species found most frequentlyinfected and apparently capable of acting as primaryhost to a large number of trematode species are

Melanoides tuberculatus with 17 forms, and Indo-planorbis exustus with 15. The number in which thecomplete life-history is worked out is extremely small,and consequently the known adult forms are few.This is hardly to be wondered at considering theintricacy of the problem.The possible definitive hosts in any particular case

may be birds, reptiles, mammals, batiachians, or

fish, all of which are parasitised by trematodes. Manyof these hosts are migratory, and may be infectedduring a short sojourn in India, so that it may be con-fidently predicted that many years will elapse beforethis subject is finally elucidated. As it is, helmin-thologists will be led to concentrate more upon life-histories than upon morphological features of theadult forms. This is a field which as yet has hardlybeen touched. Surveys of the cercarial fauna on thesame lines as set forth in this monograph should beundertaken in all parts of the world, and their resultscompared. The immensity of the field may be gaugedwhen one realises that Major Sewell has as yet derivedhis material from a comparatively small part of India.A critical survey of this important work will rest withthe systematic zoologist, but of the permanent valueof such a contribution to medical zoology there canbe no doubt.

____

THE FUTURE OF THE TUBERCULOSIS COLONY.

Two reports have just appeared synchronously, andas they represent different and, in some respects,opposite views, they give each other perspective andtogether form a useful contribution to the vexed

problem of the tuberculosis colony. The first report!deals with the Papworth Hall Colony, which hasrecently enlarged its sphere of activities by theaddition of 28 new cottages designed for patients andtheir families. When they are completed the totalnumber of houses for ex-patients will be 50. Theaverage number of patients in residence during theyear under review was 168, reaching 175 in December.In 1921, 273 patients were admitted, and it will thusbe seen that the number of patients who yearly leavethe institution for some reason or other is considerable.This does not, however, necessarily reflect on themanagement of the colony, for there must be manyundesirables of the tip-and-run stamp and others towhom the colony idea is distasteful, or for whom thesponsors of the colony have no taste. The majority ofthe patients were sanatorium failures, and some nowearning their living in the colony had been driftingfrom one institution to another for years. With one ortwo possible exceptions, no early cases were admittedin 1921, the overwhelming majority being representedby patients with advanced disease. The report

1 The Cambridgeshire Tuberculosis Colony. Report of theExecutive Committee for 1921. Printed by Papworth Industries.Pp. 34