The karyotypes of 94 species of Indian ants were examined. Their chromosome numbers range almost continuously between n=5 and 38, though the frequency distribution is bimodal with a remarkable antimode at n=11 and two modal points at n=10 and 15. Based on this bimodal distribution, Indian ants were classified into two groups: Lower-numbered species (n<_11) and higher-numbered species (n>11), the former being characterized by metacentric-rich karyotypes, and acrocentrics predominate in the latter.The three major subfamilies (Ponerinae, Myrmicinae, and Formicinae) showed a highly divergent distribution in chromosome number, ranging between n= 7-38, 6-35, and 8-27, respectively, suggesting a convergence in karyotype evolution of each subfamily, Another three subfamilies, of which only a few species were examined, had moderate or lower numbers, i.e., n=5-14 in Dolichoderinae, n=14 in Cerapachyinae, and n=12 in Dorylinae. We found four Robertsonian polymorphisms, two pericentric inversion polymorphisms, and four reciprocal translocations, three of which were fixed. Robertsonian polymorphisms were found only in higher-numbered species, while translocations were restricted to lower-numbered species. A possible biological significance for this nonrandom distribution of rearrangements is discussed with reference to karyotype evolution in ants.

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C o n t r i b u t i o n s to the C y t o l o g y of I n d i a n S c o r p i o n sThe . This is due to hypocoiling of the chromosomes. While t h e possibility of colchicine inducing constrictions u n r e l a t e d to kinetochore exists, the revealing of unseen constrictions is of interest. The c h r o m o s o m e b e h a v i o u r in Bulhus tamulus of S o u t h I n d i a is unique because, in the testicular cells of t h e s a m e individual, the following t h r e e t y p e s of orientat i o n a t m e t a p h a s e I and a n a p h a s e I are e n c o u n t e r e d : (1) t h e axes of c h r o m o s o m e s are at r i g h t angles to t h e equatorial plate, suggesting m o n o c e n t r y ( Figure d) ; (2) the axes of c h r o m o s o m e s are parallel to t h e e q u a t o r i a l axis, suggesting diffused or holokinetic n a t u r e ( Figure h); a n d (3) t h e crescentic a p p e a r a n c e of chromosomes, suggesting b i c e n t r y (Figure i). The crescentic n a t u r e of c h r o m o s o m e s of B. tamulus of Mysore S t a t e are a m e n a b l e for interpret a t i o n as inonocentric, bicentric, a n d hotokinetic. This o b s e r v a t i o n w a r r a n t s a r e a s s e s s m e n t of our opinion n o t only of kinetochore b u t also the axis relationships as criteria for designation of c h r o m o s o m e types. This is especially so in the light of t h e o b s e r v a t i o n s of RHOADES and VELKOMERSON 16 on p l a n t chromosomes, in w h i c h t h e y h a v e s h o w n 'neocentric' a c t i v i t y of n o n -c e n t r o m e r i e regions of the c h r o m o s o m e . F u r t h e r , c h r o m o s o m e s of B. tamulus d e s i g n a t e d as m o n o c e n t r i c c a n n o t be reconciled w i t h t h e fact t h a t t h e r e is a higher degree of v a r i a b i l i t y i n t e r p r e t a b l e only b y breakage and r e t e n t i o n of chromos o m e bits in t h e k a r y o t y p e . This o b s e r v a t i o n can be explained only on the basis of t h e holokinetic n a t u r e of t h e c h r o m o s o m e s . Zusammen[assung.Die C h r o m o s o m e n z a h l von Heterometrus scaber ist 96. Wird Palamnaeus swammerdami m i t Colchicin (0,2%) b e h a n d e l t , so ziehen sich die Chromos o m e n in der Pr~imetaphase I z u s a m m e n . Buthus lamulus (aus Mysore) zeigt w e i t g e h e n d variable C h r o m o s o m e n z a h l (20 28). Die L a g e der C h r o m o s o m e n in der M e t a p h a s e I und A n a p h a s e i weist auf Monozentrie, 13izentrie u n d Holokinetie.

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Abslract. Isozyme variation at six enzyme loci has been studied involving nine members of Drosophila nasuta subgroup, by employing polyacrylamide gel electrophoretic technique. Alleles at three loci namely Acph, Aph and tx-Est are found to be highly polymorphic; whereas at ~-Est locus the alleles are less variable while at a-Gpdh and To loci, the alleles are found to be least variable. Null alleles are encountered in low frequencies at rz-Est, ~-Est and c-Gpdh enzyme loci. The allelie frequencies obtained at the six enzyme loci have been utilised as a yardstick to measure the extent of genetic relationship between the species studied. The genetic identity and genetic distance between these closely-related species have been estimated by adopting the Nei's formula. These findings have been discussed with reference to earlier cytogenetic and hybridisation studies made on this subgroup.

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D. n. nasuta and D. n. albomicana constitute a pair of chromosomal races with 2n=8 and 2n=6, respectively. The F1 of these has 2n=7 and it is fertile. There exists a state of karyotypic mosaicism as evidenced by the presence of 26 types of chromosome combinations in F2, F3, and F10 populations. In the midst of this karyotypic noise, the karyotype similar to that of F1 reached 51% of the population. Implications of these findings are discussed.