598 NATHAN FASTEN 



He finds that when the early histology and embryology of the 

 testis are studied, three types of cells can be discerned, (1) nutri- 

 tive cells, (2) spermatogonial cells, and (3) cells which are inter- 

 mediate between these two. From a study of these cells Keppen 

 concludes that they have a common origin, being derived from 

 the germinal epithelium of the testis. 



Nutritive cells may often be derived from spermatogonial 

 cells by a fragmentation of the nucleus and a disintegration of the 

 nuclear wall. The nutritive cells then lie within a syncitial 

 mass of testicular protoplasm. All nutritive cells divide ami- 

 totically. 



Koltzoff ('06) produced a long paper in which he discusses 

 the sperm of Galthea squamifera, Pagurus striatus, Homarus 

 vulgaris and Portunus corrugatus. His paper contains three 

 portions dealing with, (1) the general structure of the sper- 

 matozoon, (2) the biophysics of the structures in the sperm, and 

 (3) the physiology of the spermatozoon. 



(1) General structure of spermatozoon. The sperm is similar 

 to that found in other decapods. There is a capsule or a tail 

 piece derived from the cytoplasm, and a middle piece produced 

 from the mitochondria of the cytoplasm and giving rise to the 

 flagellated arms of the sperm. The nucleus forms the head piece 

 of the spermatozoon. A central body, derived from the centro- 

 some, is also present. 



After going fully into the details of the various parts of the 

 spermatozoon, Koltzoff then tries to show how, upon a cytological 

 basis, a classification of the decapods may be attempted, and 

 actually gives such a classification. 



(2) Biophysics of the spermatozoon. Here Koltzoff discusses 

 the action of various salts on the spermatozoon. By the use of 

 solutions of K, Na, Mg, etc., the opening of the sperm could be 

 carefully studied, especially the explosion of the tail vesicle. 

 Koltzoff regards this explosion as due to osmotic changes going on 

 within the spermatozoon. 



(3) Physiology of the spermatozoon. In this section the 

 process of fertilization is discussed. When the spermatozoon 

 comes in contact with the egg it opens up and the flagellated 



