264 



Mycologia 



protoplasm contained in it is so large as to make its disappear- 

 ance practically impossible in any other way except by discharge. 

 Moreover, when the empty antheridium is pulled from the 

 oogonium a distinct circular opening can be seen in it and the 

 opening in the original membrane on the oogonium can be easily 

 made out (Fig. 4). 



The oogonia are very rarely found, and this accounts for my 

 failure to see the fertilization process. I had cultivated the 

 plant for about three months before the first oogonia appeared, 

 and they were matured during the Christmas recess. They have 

 been produced only two or three times since, and that only spar- 

 ingly, notwithstanding my efforts to induce sexual reproduction 

 by cultures on various insects and in different chemical solutions. 

 The results of some of these experiments are as follows :* 



1. On gnat in .05 per cent, haemoglobin solution in shallow 

 dish. Growth was about as extensive as in water but there was 

 a much more profuse branching, especially near the ends of the 

 hyphae. The difference was easily visible* to the naked eye. No 

 sexual reproduction. 



2. On gnat in a solution of Yz haemoglobin (.05 per cent.) and 

 3^Ca(N0 3 ) 2 (.2 per cent. sol.). About twenty oospores, all 

 with antheridia. 



3. Cultures made on gnats in shallow petri dishes gave no 

 oospores in any of the following solutions (haemoglobin in .05 

 per cent. sol. and chemicals in .2 per cent, solution in all cases) : 



Haemoglobin + KNO s 



Haemoglobin -j- K 6 H 3 (P0 4 ) 2 



Aqueous sol. of Ca(NO s ) 2 



Aqueous sol. of KNO s 



Aqueous sol. of K 0 H 3 (PO 4 ) 2 

 Cultures on gnats, flies, wasps, mosquitoes and spiders showed 

 no noticeable differences. Cultures under several inches of 

 water were unfavorable for the formation of either sexual or 

 asexual reproductive organs. 



University of North Carolina, 

 Chapel Hill, N. C. 



* The methods of Kauffman were followed in the main. See Annals of 

 Botany 22: 361. 1908. 



