ISOACHLVA 89 



a compacted complicated growth, making tiiom appear somewhat like 

 sporangia with spores. The parasite recalls a Pythium, hut no repro- 

 ductive stages were seen, in Humphrey's reference to the species 

 (which he had not found) he s[)eaks of the separation of the oogonia 

 or their initials as if it always occurred. This is incorrect, as they per- 

 haps more often hang together loosely by an angle of the stalk after 

 bending partly to one side. DeBary's figures (pi. 9, fig. 6) show the 

 oogonia still in chains though the eggs are fully formed. It is also not 

 the case, as Humphrey supposed, that all the elements of a chain of 

 initials necessarily ha\-e the same fate. Both oogonia and gemmae 

 are often combined in a chain. The tendency to constriction is sometimes 

 shown even in the sporangia, as in pi. 50, fig. 10. For other illustration 

 see Minden ('12), fig.ig on p. 520. As in 7. uttispora the spores emerge 

 slowly from the sporangium with the cilia end directed backward. 

 After emergence most of the spores show a very sluggish movement 

 close to the tip for a minute or so and then swim more actively away. 

 Not rarely a few encyst without active swimming. 



Isoachlya toriiloides easily diiTers in the presence of antheridia (though 

 often in small numbers), in the much less frequent occurrence of chained 

 oogonia and in the paler walls of the oogonia. See remarks under that 

 species. 



As in 5. asterophora and A planes Treleaseanus the sporangia are as 

 a rule exceedingly scarce or absent. In one of our collections made in 

 1921 the numerous cultures, continued for months on various media, 

 failed to produce a single sporangium. 



The following four cultures were made from No. i of January 15, 



1913: 



On corn meal agar. Good growth and many fine gemmae. No oogonia. (Xo. 2 of 

 Februarj^ 17, 1921, produced many oogonia with good eggs, also gemmae). 



In equal parts maltose 5% and peptone .01%. Good growth about one inch in diameter. 

 The only reproduction was a verj- abnormal attempt to form gemmae or eggs. The tips 

 swelled and only the apical half of the swelling was cut off. These tip cells generally 

 remained filled with moderately dense protoplasm, but in a few cases eggs were formed 

 in them. 



In egg yolk broth. Good dense growth. Many inflated oogonia. about yi with good eggs, 

 a good many enlargements as in above experiment, with cross wall in middle or nearer 

 tip of base. Some of these had eggs in tip cell. Xo other reproduction. 



On corn meal egg yolk agar. Growth strong, covering the agar, many oogonia, nearly all 

 with good eggs. Many gemmae. Oogonia almost always single and terminal. When 

 chains were formed all except the tip one remained as gemmae. .^ good many oogonia 

 were irregular in shape and so far this is the only medium in which this was the case. 

 See figs. 8 and 1 1. 



The next two cultures were made from Xo. 6 of March 27, 1914: 



