52 



MISSOURI BOTANICAL GARDEN. 



.shall 



at the Garden and remained there 



till the pond was covered for the winter. Good vegetative 



material 



th 



spring, due possibly to interference of the workmen. Decem- 

 ber 10, some of this material was brought into the laboratory 

 and placed in media made up according to Benecke's form- 

 ulae for his second series. The solutions are as follows : 





No. 1. Distilled water. 



No. 4. Like No. 3, but in place 



No. 2. Tap water (In place of pond water. ) of KNOs, KC1, .04 grm. 



No. 3. Distilled water, 100 cc. 



No. 5. Distilled water, 100 cc. 



KNO.., 

 CasPaOs, 



FesP-'Os, 

 MgS04+7H«0, .05 



.05 grm. 



.05 " 

 .05 



* * 



i i 



KNOs, 



CaCl 2 , 

 FeS04+7H 2 0, 



MgS04+7H 2 0, .05 



.05 grm. 

 .05 



.005 



i i 



i i 



i i 





It will be observed that Nos. 3 and 5 alone contain N0 3 



in solution. When Benecke experimented with S. com- 

 munis in these media he found that in the course of eleven 

 days Nos. 1, 2, and 4 produced zygotes and No. 5 showed 

 abnormal developments while in No. 3 no zygotes were 

 formed but a good vegetative growth took place. In my cul- 

 tures Nos. 1, 2, and 5 had died by the end of the third week 

 without having conjugated, but most of the filaments in Nos. 

 3 and 4 were in good condition and had apparently grown 

 slightly. Filaments in these two cultures remained alive in 

 the laboratory under conditions that seemed favorable for 

 conjugation from December 10 till after the first of April 

 when most of them gradually died, no conjugation having 

 taken place in either solution although from Benecke's 

 results it was to have been expected in No. 4. 



Solutions No. 3 and No. 4 of Benecke's third scries were 

 also used at this time. Their composition is : 



No. 3. Tap water, 1500 cc. 



NH4NO3, 



CaCl 2 , 



K 2 HP04, 



•01% 

 .005% 



. 005% 



No. 4. The same as No. 3 except 

 for the omission of the NH4NO&. 



MgS04+7H 2 . .005% 



FejiCU 



1 drop of the standard solution. 





