THE SPERM ATOGENESIS OF AGALENA N/EV1A. 145 



COMPARISON OF RESULTS. 



The earliest work on spider spermatogenesis which was done 

 under sufficiently modern methods to concern us here is that of 

 Wagner ('96^), but his complete paper, published in the Russian 

 language, is not accessible to me. From a preliminary report 

 in a German periodical ('96^) and from several short reviews, I 

 judge that his work has been rather comprehensive, including 

 the history of the germ-cells from the early spermatogonia to the 

 mature spermatozoa. His studies were mainly concerned with 

 Agalena and it is therefore with special interest that I compare 

 my results with his. In the spermatogonia he states that division 

 does not occur according to the ordinary method of karyokinesis, 

 nor is it amitotic, so one is puzzled to know what method of 

 division he did observe. He also makes the surprising state- 

 ment that the nuclei of the spermatocytes are much smaller than 

 the nuclei of the spermatogonia of the last generation. In the 

 growth period and also in the primary spermatocytic division 

 Wagner finds a peculiar nucleolus and while his description is 

 far from accurate, I have no hesitancy in saying that under this 

 term he describes the accessory chromosomes. This so-called 

 " nucleolus" has a compact, elliptical form and is always periph- 

 eral in position, never lying inside the spireme threads. In 

 the succeeding division it divides either in the plane of the equa- 

 torial plate or nearer one pole and in the latter case it is cast 

 out into the cytoplasm ( ! ). My results show that while the 

 accessory chromosomes are usually in a peripheral position, they 

 occupy a more central position in the growth period and are then 

 surrounded by the spireme threads. As to the accessory chro- 

 mosomes they do not divide at all in the first division but are 

 carried over bodily into one of the two daughter cells. 



Early workers described the spermatozoon as of a disk-like, 

 aberrant form showing no resemblance to the ordinary type. 

 Wagner was the first to discover that this peculiar looking sper- 

 matozoon, with apparently no organ of locomotion, does in real- 

 ity essentially agree in its development with the ordinary type 

 and possesses head, tail and apical body. He also demonstrated 

 clearly that the disk-like form is due to the fact that the ripe 

 spermatozoon rolls itself up in such a way that it is difficult to 



