I/O L. B. WALLACE. 



preparations when the tissues have been treated with one or the 

 other of these two solutions. In order to check as far as pos- 

 sible any changes in the cells which might take place after the 

 death of the animal the spiders were decapitated and the testes 

 rapidly dissected out while the visceral mass was immersed in the 

 fixing fluid. The paired, slightly convoluted tubular organs lie 

 embedded in the liver and contain no pigment so that in imma- 

 ture spiders it is not always an easy matter to distinguish them 

 from the spinning glands which lie ventral to them. As in many 

 other forms, a cross section of the spider testis shows a more or 

 less complete series of developmental stages, with the spermato- 

 gonia at the periphery and the cells gradually increasing in ma- 

 turity toward the lumen. In the breeding season the lumen of 

 the tube is found to be full of mature spermatozoa. Ripe sper- 

 matozoa were also taken from the pedipals and studied in smear 

 preparations, sometimes stained intra vitani and sometimes fixed, 

 before staining, by heating at the boiling point. Of staining 

 methods, Heidenhain's iron-haematoxylin and Hermann's triple 

 stain yielded the finest results. 



THE SPERMATOGONIA. 



The only comparatively recent work upon spider spermato- 

 genesis of which I have any knowledge is that of J. Wagner. 

 Unfortuately his paper is not accessible to me, but from his pre- 

 liminary report and from several full reviews, I have been able to 

 learn enough of his results to know that they differ widely from 

 mine. He mentions the fact that the spermatogonia are larger 

 than the spermatocytes even at the close of the growth period 

 of the latter. This is true of the spermatogonia of the last gen- 

 eration, but in the early generations the cells are smaller. Dur- 

 ing the rest stage, when the chromosomes become granular and 

 the chromatin granules are distributed along the linin reticulum, 

 two chromosomes are conspicuous because they take no part in 

 this disintegration (PI. I., Fig. i). From this point to the forma- 

 tion of the spermatozoon these two chromosomes can be identi- 

 fied by their shape, by their peripheral position and by the fact 

 that they show a strong affinity for safranin, in the Hermann's 

 staining method, while the other chromosomes take the gentian 



