FERTILIZATION BY EXOGAMY 



159 



but not as complete as in the gregarines; one case, Adelea ovata, is 

 interesting in that one of the conjugants is a large form similar to the 

 ordinary vegetative individuals, while the other is much smaller and 

 is derived from an individual which forms four gametes while attached 

 to the other cell, one of these gametes penetrating the larger cell, while 

 the other three degenerate and disappear. In this form also we have 



FIG. 69 



. 



$m , < Pf^. 



'.;; IS&&5 :"' i 



y 



/ 



Different forms of gametes in gregarines and coceidiidia. (After Shellack.) A, Stylo- 

 rhynchus longicollis (after Leger) ; B, a species of monocystis from Lumbricus (Cuenot); C , 

 spermatozoid of Echinomera hispida, to the left the two gametes of Pterocephalus nobilis; 

 D, the two gametes of Urospora lagidis (Brasil); E, the same of Gregarina ovata (after 

 Schnitzler); F, the same of Schaudinnella henleje (after Nusbaum); G, the same of Cocci- 

 diurn schubergi (after Schaudinn). 



what may be regarded as complete sex differentiation, since the proto- 

 plasm of the race forms individuals of male or female character, never 

 both. Schaudinn and others have shown that the difference between 

 the two conjugating forms is present in potential throughout the 

 entire series ,of forms, the first division of the fertilized egg giving rise 

 to individuals which can be identified as male or female. In this case, 



