56 



MISSOURI BOTANICAL GARDEN 



l 



and re-examined on May 30 when it was found that all the 

 material from the original lot A was either dead or greatly 

 reduced while the four cultures from lot B which had re- 

 ceived identical treatment were in good vegetative condition 

 although there were individual differences between them. 



Three other cultures started on April 29 consisted of con- 

 jugating material placed in aquaria of 500 cc, each kept in 

 bright light but not in much direct sunshine. 





No. 1 



as 



removal 



of animalculae. No. 2 was the same plus .008% each of 



Na 2 HP0 4 and K 2 HP0 4 . 



eplaced 



by NH 4 N0 3 , .016%. On May 6 the filaments in No. 1 were 

 prostrate but the few zygotes appeared to be normally devel- 

 oped. No. 2 showed excellent vegetative growth in addition 

 to the zygospores. The filaments in No. 3 were growing 

 vesctativelv and some of the zvcosnoras nnnenrpd normal hni 



mo 



many were bright green with a clear space either at one 

 or in the middle. In these clear spaces rapid Brownian 

 tion such as is characteristic of the vegetative cells could be 

 observed. May 10 apparently no additional zygospores were 

 forming and the aquaria were placed in bright sunlight. By 

 May 30 the filaments in No. 1 were entirely gone, those that 

 were alive in No. 2 were in good condition and apparently 

 taking a new start, and those in No. 3 were at a low ebb, the 



stimulating effect of the NH 4 N0 3 having passed. None of 

 the zygospores had germinated up to this time. 



Small amounts of S. Grevilleana and 8. porticalis were 

 available during a part of March and early April. March 18 

 three sets of solutions were prepared ; distilled water and Nos. 

 3 and 4 of Benecke's second series. These were used as stock 

 solutions and from each of them were started two cultures of 

 8. longata, two of S. Grevilleana and two of S. porticalis. S. 

 longata had not been found fruiting, but both of the other spe- 

 cies were conjugating at the time in nature. These cultures 

 were examined on March 22 and it was found that 8. longata 

 and S. porticalis were vegetative throughout with no evidences 



of conjugation. S. Grev 



likewise was vegetative in 



distilled water and in both solutions from No. 3 



