CHROMOSOME STUDIES 197 



shortening. The results are, therefore, not so satisfactory as 

 desired. Nevertheless, there is a certain amount of agreement 

 in the results which cannot be overlooked; it is fundamental 

 and of use in comparing genera and tribes. 



The arranging of the autosomes in three groups — nos. 1 and 

 2, nos. 3 and 4, and nos. 5 and 6 — is best brought out in the tables 

 of spermatogonia and second spermatocytes. The extreme 

 inequality of the two largest pairs may also be seen in the same 

 tables. There is one exception to this; viz., in the tables of 

 first spermatocytes. An examination of the figures of the cells 

 used, however, will show that this is due to variation in the thick- 

 ness of the chromosomes not expressed in the length measure- 

 ment. The small size of the 'accessory,' which ranks between 

 nos. 1 and 2 or close to no. 2, is evident from Table V of the 

 average of rod-shaped chromosomes. It is much too long, 

 as already explained, in the first spermatocyte cells. 



The slenderness of the sex chromosomes in the follicle cells 

 of the ovary (Table IV) is noticeable. They are 'woolly' and 

 smaller than usual. There may be some connection here with 

 their duality in the female sex. 



d. Summary for Acridium granidatus. Acridium granulatus 

 possesses the family number of chromosomes — six pairs and 

 either one or two sex chromosomes, according to the sex — and 

 shows a grouping of these pairs according to the size relations 

 which are characteristic of the family: two extremely large 

 pairs, two intermediate pairs, and two very small pairs. It 

 further bears the subfamily characters: first, in having the sex 

 chromosomes near to the smallest pair of the complex in size; 

 secondly, in having a marked inequality between the two largest 

 pairs; and thirdly, in having very small cells. It bears the generic 

 character of small sex chromosomes and nearly an extreme of 

 inequality between the two largest pairs. The chromosomal 

 relations here summarized may be readily seen in Table I for 

 rod-shaped chromosomes. 



2. Acridium incurvatus Hanc. Acridium incurvatus (figs. 4, 

 59-64; Table VII) taxonomically is closely related to granulatus. 

 The chromosomes also show this close relationship. It possesses 



