THE LAW OF BIOGENESIS 77 



The deeper one goes into this phase of Biology, 

 the more complex it becomes. 



If one now considers the structure and origin of 

 the sperm cell, it is found in its early stages to be 

 similar in form and size to the young egg-cell 

 (Fig. i8). In fact one cannot tell by the ap- 

 pearance of the earlier stages whether the cell 

 will grow into an egg or give rise to sperms. 

 Sperm cells become modified for locomotion as 

 they must make their way in the water, through 

 plant tissues, or move along passages until they 

 come in contact with the egg. 



A«A.C5piW 



Figure 23. The sperm cell of a Salamander. The long, 

 black region represents the nucleus and is the only part that 

 participates in fertilization. 



Fig. 23 is an enlarged drawing of a sperm cell 

 of a salamander. It consists of a head, middle 

 piece and tail. The head is the condensed nucleus 

 and consists of a compact mass of chromatin; the 

 tail is all that remains of the cytoplasm; while 

 the middle piece is a minute structure intimately 

 associated with the future division of the cell. 



Omitting the technical aspects of some of the 

 details, one can now make a comparison between 



