ON THE SEXUAL DIFFERENCES OF THE CHRO- 

 MOSOME GROUPS IN GALGULUS OCULATUS. 1 



FERNANDUS PAYNE. 



An examination of the spermatogenesis of Galgulus oculatus 

 together with a comparison of the male and female chromosome 

 groups, has brought to light a new type of sexual difference in 

 respect to the chromosomes. With this is correlated a new type 

 of distribution of the chromosomes in the formation of the 

 spermatozoa. On account of the interest of these facts, both in 

 themselves and in relation to the theory of sex determination 

 advocated by McClung, Stevens and Wilson, it seems desirable 

 at the present time to offer this preliminary note on the subject. 

 As soon as additional material can be procured, I hope to study 

 and describe the facts more in detail ; but those here presented, 

 are shown beyond a reasonable doubt by the material now avail- 

 able. 2 



The number of chromosomes in the first maturation divisions 

 is somewhat difficult to determine with certainty, owing to the 

 fact that associated with them are always a greater or less number 

 of deeply staining bodies resembling yolk granules, large numbers 

 of which are also present in the general protoplasm of the sperma- 

 tocytes in this genus (Fig. i, F, G and H). I hope to overcome 

 this difficulty in later work by means of differential stains. These 

 granules can, however, be distinguished from the chromosomes 

 by their smaller size and spherical form. A comparison of a 

 number of equatorial plates of this division shows that the number 

 of chromosomes is almost certainly twenty. All of these divide 

 equally so that the secondary spermatocytes receive twenty 

 chromosomes each. In the specimens figured the chromosomes 

 do not show any definite arrangement, but in some cases, fifteen 



1 By some later writers, the generic name of this species is given as Gelastocoris. 

 For the sake of avoiding confusion, I shall retain the term Galgulus. 



2 This material was collected by Prof. E. B. Wilson, in North Carolina, and given 

 me for study. I wish to thank him for helpful suggestions and criticisms. He also 

 kindly made the photographs for me. 



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