Spermatogenesis iu spiders. 553 



The contraction goes on until tlie autosomes have the thick 

 heavily-staining- compact forms which are so characteristic of them 

 during- the first division (Fig-. 111). Even at this time, one may 

 see in some of the autosomes a distinct split running the length 

 of the bodies, a split which undoubtedly represents that appearing 

 earliei'. 



During tlie first division we have two types of autosomes in 

 this form, which are much like those shown for Maevia vitfata in 

 Figs, F and G. The way in which these bodies separate is shown 

 in Figs. H and I. 



In the first division the accessory chromosome is made up of 

 two elements, and these pass to one pole early in the division 

 (Fig. 112). A ratiier constant feature of the first division spindle is 

 the precocious division of a very small chromosome shown in the 

 figure. In equatorial view the autosomes lie well apart and counts 

 are made with ease (Fig. 113). During the second maturation period 

 the autosomes enter a resting stage. 



The accessory chromosomes divide early. The autosomes appear 

 as elongated rods, as shown in Fig. L for Maevia vittata. 



Number of chromosomes. 



Repeated counts gives the haploid number of autosomes as 12 

 (Fig. 113), The constitution of this form then is as follows: 

 Autosomes 24 



Accessory chromosome 2 



Total 26 not including the planosomes. 



Spermatogenesis of Lijcosa conmiunis. 



As a representative of the family of Lycosidae — the wolf 

 spiders — the common form has been chosen. A study of this 

 family seemed desirable because Montgomeet has published a des- 

 cription of the spermatogenesis of a closely allied form, Lijcosa insopita. 

 The description which he gives of the accessory chromosome has 

 been called into question by Beret working on Epeira sclopetaria 

 and by Wallace working on Agalena naevia, but no one has ever 

 studied a member of this family in order to clear up the subject. 



There are four points of especial interest for us in Mokt- 

 gomeey's description. I. He derives the accessory chromosome from 

 two spermatogonial chromosomes which conjugate during the growth 



