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15.9. 1967 Specialia 769nomial formula, separately, for every testee. In case of itbeing smaller than 0.05 the identification was consideredto be good , i.e. the guessing was judged to hav e nopractical effect.Resul ts . The distribution of the subjects into < 0.05( good ) and >= 0.05 chance prob abil ity classes is illus-trated in Table I. About a]s of the testees attained atleast the score 9 which was the lowest good answer.

Table I. Distribution of subjects according to the identificationability level

No. of No, of Relativecorrect subjects frequencyresponsesChance 0.05 ( good ) 9, 10 11 0.31Proba bilit y 0.05 0-8 24 0.69

Tot al 35 1.00

Table II illustrates response patterns classified by theage of the baby. Only own baby responses are included.The identification numbers of o w n - o w n responses permother were divided by the maximum attainable;numbers of other-own responses were treated in the sameway, These statistics are denoted by Me and Mi in theTable and considered as average numbers of the 2 typesof responses in relation to the maximum possible numberof the same response types. The number of mothers ineach age group is small and no clear increase or decreaseis to be seen in either series.Discus s ion . This study shows that it is possible forsome mothers to identify the hunger cry signals of theirown new-born baby. A few were able to do this when thebaby was only 1 day old, supporting the fact that indi-vidual differences exist, in any case, in the cries of someof the babies at this age. This may also indicate the pos-sibility of innate identification.This study does not take into consideration the psycho-logical factors involved in early identification and we donot know as yet what influence mental and physicalstress, cultural, social and educational differences mayhave on this identi fication s

Table II. Correct and incorrect identifications with response ownbaby , according to the age of the baby

Age of baby, days1 2 3 4 5 6 7 Total

No. of 5 5 5 5 5 5 5 35mothersMc 0.60 0.50 0.40 0.60 0.50 0.60 0.80 0.57Mi 0.18 0.23 0,25 1.18 0.35 0,15 0.15 0.21

Me, No. of correct identifications of the type own-own per mother,divided by maximum possible amount (2.0) of the same type ofresponses. M i No. of incorrect identifications of the type other-ownper mother, divided by maximum amount (8.0),of the same type ofr e s p o n s e s

Z u s a m m e n [ a s s u n g . Es wurden die FAhigkeiten derMfitter gepriift, das Hungerschreisignal ihrer eigenenNeugeborenen w~hrend des Wochenbettes zu identifi-zieren. Man ha t festgestellt, da ss es ffir etwa */z der ge-testeten Miitter m6gtich ist, vorher auf Band aufgenom-mene Stimmen der eigenen Kinder schon in diesemfriihen Alter wiederzuerkennen.E. H. VALANNE, V. VUORENKO S K I T. J. PARTANEN,J. LIND and O. WASz-HoCKERT

D e p a r t m e n t o / P e d i a t r i c s , U n i v e r s it y o / O u l uFin land) , and The Wenner -Gren ResearchLaboratory , Stockholm Sweden ), l Oth A pr i l 1967.

8 Acknowledgment: this study has been supported by t h SemperFund for Nutritional Research, Sweden and by the FinnishMedical Research Committee.

T h e S o m a t i c C h r o m o s o m e s o f L i z ar d S p e c i e s:Gekko gecko I guana iguan a a n d Crotaphytuscol lar is:Recent technical advances, particularly the leucocyteculture method, have greatly facilitated progress in mam-malian cytogenetics. The description of correct karyo typesamong lower animals is also expanding as techniques formamm alia n cell culture are adapte d to these organisms.We wish to describe the diploid chromosome number andthe somatic karyotypes of 3 lizard species: Gekko gecko(Gekkonidae, :Reptilia), I g u a n a i g u a n a (Iguanidae, Rep-tilia), and Crotaphytus coltaris (Iguanidae, Rep~lia).In G. gecko and I . i guana , chromosomal preparationsWere obtained from phytohemagglutinin stimulated pe-ripheral blood cultures. All chromosomal preparations

were ma de follo wing th e me th od of ~[OORHEAD et al.1with minor modifications.Measurements were made on karyotypes derived fromwell-spread metaphase plates to establish the idiogramof each species. The length of each chromosome (Table)is given as the percentage of the total haploid complementin G. gecko and the percentage of the haploid macro-chromosomal complement in the Iguanids. I t is obviousthat the macrochromosomes of I . i g u a n a and C. collarisare quite similar in the length of the various elements andin their associated arm ratios. Arm ratios were not calcu-

x p. S. MOORHEAD, P. C. NOWELL, W. J. MELLMAN, D. M. BATTIPPSan d D. A. HUNGERFORD, Expl . Cell Res. 20 613 (1960).

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77 Spec iali a EXPERIENTIA 2319Relative lengths a nd arm ratios (mean a nd s tand ard error) of the chromosomes of 3 lizard species based on percentage of the haploid comple-m e n t

Chromc~ome Relativ e Arm ratio Macroehromo- Relative Arm ratioNo. length (%) some No, length (%)

Gekko gecko (based on 10 karyotypes) Iguana iguana (based on 10 karyotypes)1 13.74 4- 0.204 1.65 4- 0.067 1 23.59 4- 0.232 1.20 4- 0,0422 12.22 4- 0,183 1.82 ~ 0.071 2 22.00 4- 0.376 1.54 q- 0.0533 9.24 q- 0.16 0 2.01 :~z 0.09 2 3 17.23 4- 0.28 6 1.14 -4- 0.0244 7.98 -4- 0.201 4 15.46 4- 0.27 4 1,18 -b 0,02 05 7.28 4. 0.132 5 12.82 4- 0.I55 1.16 4- 0.0176 6.60 4- 0.130 6 8.90 4- 0.136 1.17 4- 0.0207 5.70 4. 0.1388 5.30 4- 0.045 Crolaphylus collaris (based on 8 karyotypes)9 4.94 4- 0.09210 4.42 4- 0.132 1 23.85 4. 0.335 1.24 -4- 0.02011 3.88 4- 0.147 2 22.68 4. 0,339 1.82 q- 0.07812 3,24 4. 0,102 3 18.19 4. 0.447 1.16 -Jr- 0.02613 2.94 4. 0,081 4 15.53 4. 0.25 4 1.25 4- 0.07914 2.68 4. 0.087 5 11,56 -b 0,224 1.17 -4- 0.02'215 2.42 4. 0.160 6 8.19 4. 0~231 1.25 4- 0.03316 1.90 4- 0.05517 2.60 -4- 0.030 4.2 4 4- 0.08818 1 ,72 4. 0.093 1.16 q 0.07419 1.20 4. 0.084 1,06 4- 0.039

l a t e d f o r t h e t e l o c e n t r i c e l e m e n t s of G. gecko n o r w e r e t h em i c r o c h r o m o s o m e s o f t h e o t h e r 2 s p ec i es m e a s u r e d .Gekko gecko. L e u c o c y t e c h r o m o s o m e s o f 1 m a l e a n d 1f e m a l e a s w e l l as m e t a p h a s e f i g ur e s f r o m t h e p r i m a r yh e a r t a n d l u n g c u l t u r e s o f a s e c o n d m a l e w e r e e x a m i n e d .T h e d i s t r i b u t i o n o f c h r o m o s o m e c o u n t s ( 2 5 0 c e ll s ) y i e l d e da d i p l o i d n u m b e r o f 2 N = 3 8 i n al l t i s s u e s a n d a n i m a l sw i t h n o a p p a r e n t h e t e r o r n o r p h i c p a i r i n e i t h e r s e x in -d i c a t i v e of s e x c h r o m o s o m e s . T h e k a r y o t y p e ( F i g u r e 1 ),c o n s i s t s o f 3 p a i r s o f l a r g e s u b m e t a c e n t r i c e l e m e n t s ; 2 6t e l o c e nt r i c c h r o m o s o m e s i n a g r a d u a t e d s e ri e s w h i c h c a nb e f u r t h e r d i v i d e d i n t o g r o u p s o f 6, 6 a n d 1 4 ; 1 p a i r o [s u b t e l o c e n t r i c c h r o m o s o m e s a n d 4 m e t a c e n t r i c e l e m e n ts .N o m i c r o c h r o m o s o m e s w e r e o b s e r v e d i n t h i s s p ec i es .Iguana iguana. L e u c o c y t e m e t a p h a s e s f r o m 1 m a l e a n d1 f e m a l e w e r e e x a m i n e d a s w e l l a s e a r l y p a s s a g e c e l l sf r o m h e a r t , k i d n e y , s p l e e n a n d l i v e r of 2 a d d i t i o n a l m a l e s .T h e d i p l o i d n u m b e r p r o v e d t o b e 2 N = 3 4 w i t h t h ep r e s e n ce o f b o t h m i c r o - a n d m a c r o c h r o m o s o m e s . T h ek a r y o t y p e ( F i g u r e 2) c o n s i s t s o f 1 2 m a c r o c h r o m o s o m e sa n d a n a v e r a g e o f 22 m i c r o c h r o m o s o m e s ( m o d e i n 35 2c o u n t e d c el ls ). T h e m a c r o c h r o m o s o m e s , e x c e p t f o r t h es e c o n d l a rg e s t p ai r , a r e a l m o s t p e r f e c t l y m e t a c e n t r i c . T h es e c o n d l a r g e s t p a i r is s u b m e t a c e n t r i c . M o s t o f t h e m i c r o -c h r o m o s o m e s a p p e a r t o b e m e t a c e n t r i c ; h o w e v e r , i nm a n y c a se s t h e se e l e m e n t s a r e t o o s m a l l f o r a c c u r a t em o r p h o l o g i c a l d e s c r i p t io n . N o e v i d e n c e f o r h e t e r o m o r -p h i s m o f a se x c h r o m o s o m e p a i r i n e i t h e r s e x w a s o b v i o us .Crotaphytus colluris. C u l t u r e d c e l l s d e r i v e d f r o m p r i -m a r y l u n g a n d h e a r t c u l t u r e s o f a s in g l e m a l e w e r ee x a m i n e d . A t o t a l o f 4 2 m e t a p h a s e p l a t e s y i e l d e d a d i p l o i dn u m b e r o f 2 N = 3 6 w i t h 1 2 m a c r o c h r o m o s o m e s a n d 2 4m i e r o c h r o m o s o m e s ( 2 0 c el ls ). The k a r y o t y p e ( F i g u r e 3)

Fig. 1. The ka ryotype of Gekko gecko 2N ~ 38). Note the absence ofmierochromo~omes.

I litmJm , .....

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15.9. 1967 Speeialia 77i s q u i t e s i m i l a r t o t h a t o f I . iguana. T h e s e c o n d l a r g e s tp a i r of m a c r o c h r o m o s o m e s i s s u b m e t a c e n t r i c w h i l e t h er e m a i n i n g 1 0 a r e m e t a c e n t ri c . H o w e v e r , a n a d d i t i o n a lp a i r o f m i c r o c h r o m o s o m e s i s p r e s e n t i n t h i s s p e c i e s .P A IN T E R 2, u s i n g s p e r m a t o g o n i a l c e l ls , r e p o r t e d 2 N = 3 6o r 3 8 f o r C , collaris w i t h 1 2 m a c r o c h r o m o s o m e s a n d 2 4o r 2 6 m i c r o c h r o m o s o m e s .T h e c h r o m o s o m e n u m b e r s o f t h e G e k k o n i d s r a n g e f r o m3 2 - 4 6 a m o n g t h e s p e c i e s s t u d i e d S , 4. N AK AM UR A r e p o r t e d2 N = 3 8 i n Gekko ~aponicus i n 1 9 3 2 , b u t o f f e r e d n ok a r y o t y p e 5. T h i s i s t h e i d e n t i c a l n u m b e r o b s e r v e d i n G .gecko I n a g r e e m e n t w i t h M A TT HE Y s, t h e a b s e n c e o fm i c r o c h r o m o s o m e s i n G. gecko i s c h a r a c t e r i s t i c f o r t h e

, ..: : ~, ., :, r,- , 44':%

e n t i r e G e k k o n i d g r o u p ( as w e l l a s t h e S c i n c i d a e ) , w h i l ea l m o s t a l l o t h e r l i z a r d s p o ss e s s b o t h m i c r o - a n d m a c r o -c h r o m o s o m e s . K a r y o t y p i c d a t a f r o m s t u d i e s of s o m el i z a r d s h a v e a l r e a d y a i d e d i n e l u c i d a t i n g d i f f i c u l t i e s i ns p e c i es c l a s s i f i c a t i o n b a s e d o n g r o s s m o r p h o l o g i c a l c r i t e r i as o l e l y e,7. A l t h o u g h t h e n u m b e r a n d m o r p h o l o g y o f t h em a c r o c h r o m o s o m e i n I . iguana a n d C. collaris a r e s i m i l a r ,t h e m o d a l n u m b e r o f m i c r o c h r o m o s o m e s d i f f e rs in t h e s e2 s p e ci e s . T h e r e f o r e , t h e n u m b e r o f m i c r o c h r o m o s o m e sm a y s e r v e a s a n a d d i t i o n a l p a r a m e t e r b y w h i c h t oc l a s s i fy t h e s e a n i m a l s .

S e x c h r o m o s o m e h e t e r o m o r p h i s m i n r e p t i le s i s s t il l a na m b i g u o u s p r o b l e m s A l t h o u g h s n a k e s a p p a r e n t l y m a n i -f e s t f e m a l e h e t e r o g a m e t y ~ -1 1, l i z a r d s d o n o t l i,x 3. S u c hs e e m s t o b e t h e c a s e w i t h t h e s p e c i e s r e p o r t e d h e r e i n . S e xc h r o m a t i n m a s s e s w e r e n o t o b s e r v e d i n t h e i n t e r p h a s en u c l e i o f c u l t u r e d c e l ls f r o m e i t h e r I : iguana o r G. gecko.T h e l a c k of o b v i o u s se x c h r o m o s o m e d i m o r p h i s m m a yb e d u e t o t h e f a c t t h a t : (1 ) s e x c h r o m o s o m e d i f f e r e n t i a t i o ni n so m e s p e c i e s o f r e p t i l e s is y e t t o o p r i m i t i v e t o b eo b s e r v e d m o r p h o l o g i c a l l y ; o r , ( 2) s e x i n t h e s e s p e c i e s m a yb e d e t e r m i n e d a t t h e g e ni c r a t h e r t h a n t h e c h r o m o s o m a lle ve l x4.

Zusammen/assung. D i e s o m a t i s c h e n C h r o m o s o m e n d e r3 E i d e c h s e n a r t e n Gekko gecko ( 2 N = 3 8 ) , I guana iguana( 2 N = 3 4) u n d Crotophytus collaris ( 2 N = 3 6 ) w e r d e nd a r g e s t e l l t . G. gecko b e s i t z t m e t a z e n t r i s c h e , s u b t e l e o z e n -t r i sc h e u n d t e l e o z e n t ri s c h e E l e m e n t e , a b e t k e i n e M i k r o -c h r o m o s o m e n . I . iguana u n d C. collaris b e s i t z e n M a k r o -c h r o m o s o m e n ( 6 P a a r e ) u n d M i k r o c h r o m o s o m e n . B e i d e nA r t e n G. gecko u n d I . iguana w a r e n i n k e i n e n y o n b e i d e nG e s c h l e ch t e r n h e t e r o m o r p h i s c h e C h r o m o s o m e n p a a r e n a c hz u w e i s e n .

Fig. 2. The k aryotyp e of Iguana iguana (2 N = 34).

Fig. 3. The kary otype of Crotaphytus coUaris (2N ffi 36).

I- V~.M . COHE N, CH. C . HUANGa n d H . F . C L A R K

Div is ion o /Human Gene t ic s , Department o /Pedia tr ic s andVirology Laboratory, State University o] New York atBu/[a lo School o /Me dic in e and Buf fa lo s Chi ldren sHospital , Bu]falo (New York 14222) and Springvil leLaboratories, Roswell Park Memorial Insti tute ,Springvil le (New York USA), 75th May 1967.

s T. S. PAINTER, J. exp . ZooL 3d, 281 (1921).s R. MATTH~Y, Les Chromosomes des Vert~bres (Librair ie de l Uni-versitd, F. Rough, Lausanne 1949).P. C. ALTMAN an d D. S. DITT,MER,Growth: Including reprodeaionand morphological development (Fedn Proe. Fedu Am. Soes exp,Biol. 1952).K. NAKAMURACytologla 3, 156 (1932).6 G. C GORMAN Nature 208, 95 (t965).7 L. A. Pm ~oeK , Sc ience 1~9, 539 (1965).8 R. MATTHEY, Ad v. Ge net . 4, 159 (1951).W. B~eAK, M. L. BECAK an d H . R. S. NAZERETH, Cyto genetie s I,305 (t962),a0 H. R . K om~L, Ex pe rie nt ia 18, 173 (1962).n W. BEeA~, M, L, BECAK, H. R. S. NAZERETa and S. OH so,Chromosoma 15, 606 (1964).~ R. MATTHEV an d J, M. VAN BRINK, Ex pe rie nti a 12, 53 (1956).l a j M . V A N BRI N K Chromosoma 70, 1 {1959).x4 Suppo rted b y Project No. 417 from the U.S. Children s Bureauand Grant No. 08737 from the National Cancer Institute.