No. 2.] THE SPERMATOGENESIS OF LUMBRICUS. 283 



body in the developing cells, and can be readily demonstrated 

 by the use of most stains. 



The position of the archoplasm in the spermatozoa of differ- 

 ent animals is interesting because of its bearings on fertiliza- 

 tion of the &^g and origin of the male attraction center within 

 the Q.gg. The origin of this body within the ^^^ has been 

 observed in only a few cases. Fick ('93) followed its history in 

 the fertilization of the Axolotl egg and found that its Anlage is 

 the middle-piece of the spermatozoon. Foot ('94) has recently 

 examined the fertilization and maturation processes in Allolo- 

 bophora foetida {Ltimbriats foetida), and asserts that the attrac- 

 tion center seems to arise from the middle-piece of the sperma- 

 tozoon. Fol ('91) asserted that in the fertilization of the 

 echinoderm egg, the male attraction sphere originates from 

 the anterior tip of the spermatozoon, but Wilson ('95) has 

 clearly shown that Fol's interpretation of the fertilization 

 process in echinoderms was erroneous. Besides demonstrating 

 the absence of Fol's "Quadrille of the Centers" he shows 

 that the attraction sphere in the fertilized eggs of Toxopneustes 

 variegatits is derived from the middle-piece of the spermatozoon, 

 which rotates through an angle of 180 degrees after entering 

 the Q.gg. Mathews ('95) has observed the same rotation in the 

 fertilized eggs of Asterias and Arbacia. In all of these cases, 

 therefore, where the process of fertilization has been carefully 

 followed, the "sperm center" originates from the middle-piece 

 of the spermatozoon. 



What now is the relation between the archoplasm {i.e., 

 sperm center) in the middle-piece of the spermatozoon, and the 

 archoplasm of the early germ cells 1 Is the " sperm center " 

 composed of the same substance as the archoplasm of the 

 spermatocytes and spermatid 1 



There are unfortunately too few cases where the fertilization 

 processes have been carefully followed out to enable us to 

 decide this question, and in the cases cited above the results of 

 different investigators are, in a measure, contradictory, while 

 the results obtained by other observers apparently cohere. 

 For example, in the spermatogenesis of the echinoderms. Field 

 ('93) has followed the centrosome from the early spermatic 



