CoKER AND Hyman I Thraustotheca clavata 89 



laterally biciliate form. Finally they encyst again and sprout. 

 At the time of the final encystment the spores are of course 

 spherical, measuring about 12.5/^ in diameter. 



The oogonia are borne singly on short, straight, perpendicular 

 branches from the secondary hyphae, rarely from the primaries. 

 At the time when the eggs are fully ripe the oogonia measure 

 about 59/x in diameter. They are spherical, smooth, and very 

 slightly pitted, the pits appearing only after staining with chlor- 

 zinc-iodide. Each oogonium contains from i to 8 eggs (fig. 6). 

 The usual number of eggs is either 4 or 6. Ripe eggs are spher- 

 ical or slightly angular from pressure, excentric, with a single 

 large peripheral oil globule (fig. 6). They are very constant as 

 to size with a diameter of from 20/x to 22/x. The antheridial 

 branches also arise from the secondary hyphae. They are long, 

 very crooked, and quite stout. The ends of the antheridial 

 branches become closely applied to the surface of the oogonium, 

 and club-shaped antheridia are cut off from their tips (fig. 7). 

 In many cases it was noted that the antheridium gave off a short 

 tube which entered the oogonium and became applied to an egg 

 (fig. 6). The actual fertilization of the egg was never seen but 

 the antheridia were observed to become empty during the ripen- 

 ing of the eggs. In no case was it found that an antheridial 

 tube became attached to an oogonium arising from the same 

 hypha as itself. 



The formation of the oogonia and eggs may be easily watched 

 in this species. The protoplasm of the hypha flows out into the 

 oogonial branch, rapidly packing it with densely granular sub- 

 stance. The tip of the branch swells into a rounded sphere 

 which is packed with a very dense protoplasm. This tip is then 

 cut off from the oogonial branch by a cross wall and the oogo- 

 nium has been formed. 



The substance within the oogonium is at first entirely homo- 

 geneous. After some time it may be noticed that oil drops are 

 collecting at the periphery of the protoplasmic mass (figs. 7, 8, 

 and 10). The protoplasmic mass then begins to divide, the divi- 

 sion beginning at the center and traveling towards the periphery. 

 At first a clear space appears in the center of the mass from 

 which radial spaces gradually extend outward. The eggs when 



