308 BOTANICAL GAZETTE [May 
readily enough have come from several groups of alge. Let us 
again suppose such types of fungi to leave the water and livea 
terrestrial life as parasites or saprophytes. Their gametangia, 
unable to discharge the gametes into an aqueous medium, and 
yet required to satisfy the chemotactic influences associated with 
sexuality, might find the most satisfactory escape from the diffi- 
culties of their environment in fusing with one another. Insuch 
mingling of the cytoplasm of two gametangia would be presented 
the possibility of the fusion in pairs of many of the sexual nuclei 
(gametes) in a protoplasmic medium instead of water. From 
such conditions might have arisen a zygospore similar to that of 
the Mucorales. 
If a method of zygospore formation should develop in the 
manner indicated above, what further changes might be expected 
with the gradual evolution and specialization of the forms? It 
does not seem unreasonable to suppose that the same tendencies 
toward the differentiation of sex would appear here as are mani- 
fested in all groups of the alge. It might be advantageous to 
reduce the number of gametes (sexual nuclei) to provide the 
functional female ones with a special supply of cytoplasm, and 
thus to organize one or more oospheres inside a female game- 
tangium. The furthest extreme of such sexual differentiation 
would be similar to the conditions illustrated by Albugo candida, 
With its single functional female nucleus (gamete), associated 
with a large supply of cytoplasm (ooplasm). We have in Albugo 
éliti an example of what might be imagined as an earlier stage In 
such a process of differentiation, for the number of functional 
sexual nuclei or gametes is large. Nevertheless, the female 
gametes are collected in a differentiated region of the cytoplasm, 
the oosphere, and this peculiarity would be a decided advance 
over the conditions illustrated by the moulds. ; 
It should be noted that the oospores resulting from this dif- 
ferentiation of sex would bear no homologies to analogous 
structures among the alga. They would furnish, on the contrary, 
another illustration of the well established fact that many 
divergent lines of thallophytes have developed, independently 
of one another, the oosporic method or sexual reproduction 
