600 NATHAN FASTEN 



The spermatogonia divide without the formation of a spireme, 

 and the maturation divisions follow one another quickly. Bin- 

 ford states that there is a long period of synapsis, but does not 

 go into any of the details of this important process. 



During the transformations of the spermatid the nucleus 

 becomes reduced in size and uniform in consistency. It becomes 

 oriented to one end of the cell, while at the opposite end a clear 

 vacuole appears in the cytoplasm, which gives rise to the capsule 

 of the spermatozoon. The flagella-like arms arise from a mitro- 

 chondrial mass, which becomes segregated from the cytoplasm 

 and is deposited as a ring between the nucleus and the capsule. 

 The central body lying in the center of the capsule arises from a 

 granule (probably the centrosome) on the proximal side of the 

 capsule. At the distal end of the central body a vescicle arises 

 which soon changes into an inner tubule. 



In hypotonic solutions of various salts the central body be- 

 comes lengthened and there occurs an eversion of the inner 

 tubule, with the result that it is turned inside out. Binford 

 believes that this is the force that tends to drive the sperma- 

 tozoon into the egg, for he found that when the sperm comes in 

 contact with the egg, under normal conditions, such an eversion 

 occurred. The capsule of the spermatozoon is applied to the 

 shell of the egg, and the everted inner tubule and the capsule 

 with its contents are then driven through the covering into the 

 interior of the egg. The nuclear cap remains behind and does 

 not penetrate the egg at all. 



To bring this method of fertilization in line with the chromo- 

 somal basis of heredity, he postulates that the contents of the 

 capsule may be derived from the nucleus of the spermatid, and 

 is probably oxychromatin, which deposits basichromatin after 

 it enters the egg and so gives rise to the chromosomes in the male 

 pronucleus. 



Reinhard ('13) studied the development of the spermatozoon 

 in Astacus leptodactylus and found that the head consisted 

 mainly of the nucleus; the middle piece, or the flagellated arms 

 resulted from the mitochondria, while the tail vesicle arose 

 from the rest of the cytoplasm. 



