VITALITY 



2S1 



bring about, one leading to relatively greater stability, storage of 

 metabolic products and relative inactivity, the other leading to a 

 more kinetic organization with freedom from metabolic products. 

 As one would expect there is every gradation in the relative differen- 

 tiation of anisogametes, from hologametes to egg and spermatozoon. 

 If the differentiation in two directions is manifested at the very 

 outset of a life cycle in organisms developing from zygotes, one 



y i :>■_/ jJ-y^\-i :.w Y-fr > ... • -. -l -A 



Fig. 144. — Gametes of Gregarines and Coccidia. A, male and female gametes of 

 Stylorhynchus longicollis; B, Monocystis sp.; C, spermatozoid of Echinomera hispida, 

 to the left the two gametes of Pterocephalus ndbilis; D, gametes of Urospora lagidis; 

 E, of Gregarina ovata; /•'. of Schaudinella henleae; and G, of Eirru ria schubi rgi. (From 

 Shellack after Leger, Cut-not, Brasil, Schnitzler and Schaudinn.) 



ultimately giving rise only to macrogametes, the other only to 

 microgametes, then we are dealing with a matter of inheritance 

 or fundamental organization and not with progressive or cumulative 

 differentiation through metabolic activities. In such instances, 

 particularly if the differentiations are manifested by structural 

 features whereby one type can be distinguished from the other 

 we are justified in using the term sex in the same sense as used for 

 Metazoa. 



