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WM. H. WESTON 
non-sexual reproduction. Under pure culture conditions, also, my- 
celia, grown on sterilized flies, or transferred from various nutrient 
solutions to water, developed Achlya zoosporangia followed only by 
resistant spores. 
The reactions of the fungus when subjected to culture conditions 
designed to induce sexual reproduction will be discussed later, the 
phases of its normal development now being considered in detail. 
Zoosporangia. — ^The vegetative mycelium of the fungus, whether 
in gross or pure culture, consists of non-septate, branching hyphae 
that show no apparent difference from those of other species of Achlya. 
In gross cultures, as has been stated above, the first reproductive 
structures to which the mycelium normally gives rise are zoosporangia. 
In pure cultures, well nourished mycelia can be induced to form zoo- 
sporangia in abundance by a distinct and rapid decrease of the food 
supply according to the methods of Klebs (7), Kauffman (6), Horn 
(4) , and Pieters (15). 
The process of sporangium development and spore formation in 
this Achlya is quite normal, agreeing in its external features with the 
description of Ward (17) for Achlya polyandra de B., and Humphrey 
(5) for Achlya Americana Humph. No detailed description need 
therefore, be given here. 
The fully developed sporangia are cylindrical (Fig. 12) to fusiform 
(Fig. i) in shape, and vary greatly in size. They are formed in basi- 
petal series, or renewed by side branching (Fig. 12), but never by 
growth of the sporangiophore through the empty sporangium. 
Escape of the sporangiospores from the sporangium is through a 
terminal papilla of dehiscence; and in connection with the mouth of 
the sporangium is formed the sphere of the encysted spores (Fig. i) 
which is characteristic of the genus Achlya. From each encysted 
spore (Fig. 2) thus situated there may emerge under the proper con- 
ditions a zoospore of the laterally biciliate Achlya type. The en- 
cysted spores average 10.5 ix in diameter while the zoospores measure 
about 12.5 by 9 ju. 
In shape these zoospores are ovoid with a flattened side bearing a 
longitudinal groove or sinus from which arise the two cilia (Fig. 3). 
It is unfortunate that investigators have been content to describe and 
figure this type of zoospore in the Saprolegniaceae as "bean " or " kid- 
ney" shaped. A careful examination of the living spores under a Zeiss J 
water-immersion lens readily proves these terms to be inadequately 
