250 PHYTOPHTHORA MEADII n. Sp. ON IJEVEA BRASILIENSIS 



series made on 9th January, 191G, was examined on IGth February, 1916, 

 and oogonia were found. A third of this series sub-cultured on 1st February, 



1916, contained oogonia when examined on 17th February, 1916. In these 

 three cultures the interval between date of sub-culturing and that of observing 

 oogonia was 59, 38 and 17 days respectively. On 7th December, 1915, several 

 sub-cultures were made on Qiiakcr-oats-agar at the same time and from the 

 same material as those just described. In one of these oogonia were found 

 on 4th February, 1916. For a long time, though we put sub-cultures in what 

 we thought were exactly the same conditions, no more oogonia were found. 

 On 30th June, 1917, a Heven fruit with a sMght discoloration on its surface was 

 kept overnight in a moist chamber. Next morning sporangia growing out 

 of it were plated out in glucose-agar, and on 4th July one germinating as a 

 conidium was placed in each of 4 Quaker-oats-agar tubes and in each of 4 

 French-bcan-agar tubes. On 17th August one Quaker-oats-agar tube and 

 one French-bean-agar tube were examined, but no oogonia were present. On 

 7th September other two tubes were examined with negative results, and on 

 25th September these two tubes were again examined with negative results. 

 On 18th October a third set of two tubes was examined with negative results. 

 On 10th November the fourth set of two tubes was examined, and oogonia 

 were found in the Quaker-oats-agar tube only. In these five tubes alone have 

 oogonia developed, yet we have examined over 100 cultures specially grown 

 for this purpose on various kinds of media at different times during 1916 and 



1917. Thus the oogonia in the first four instances were got from the same 

 strain, and this is a similar experience of other investigators of this genus. 



The first tube that produced oogonia sown on 7th December, 1915, and 

 examined on 4th February, 1916, contained 30 of them all of which were mature, 

 maturity being decided by the oospores having a distinct coloration and a 

 thickened wall. In this tube were 6 oogonia whose length was greater than 

 40/x, and only one oogonium of this size (it being 44 x 38)U,) has been seen in 

 subsequent cultures. The average measurement of these 6 oogonia was 

 45 X 41 /A — the largest being 49 X 45/a, and the smallest 42 y 35//. The oospores 

 they contained, however, were very little larger than the general average, 

 their average being 26 x 25/a, the largest 28 X ^G/x, and the smallest 24 x 22/x. 

 Indeed larger oospores have been found in other cultures though the latter 

 were contained in oogonia that did not measure above 38/x. 



From the tube sown on 9th January, 1916, and examined on 16th February, 

 1916, 30 oogonia were obtained. They were much more uniform in size than 

 those from any other culture. This does not seem to be because they were 



