REPORT OF THE SOCIETY 87 



PH value of the medium. Burkholder (2: 1919) makes a similar statement in 

 connection with his study of F. martii phaseoli. 



General!}', speaking, therefore, the concentration of the H-ions in the me- 

 dium does not appear to be the only limiting factor for growth characteristics, 

 but is of importance when taken in conjunction with other factors, such as 

 temperature, and the composition of the medium. 



Summary. 



1. F. lathyri Taub. has been isolated from the roots of wilted sweet peas 

 F. gibbosum A. & W.,F. lanceolatum Pratt, and F. solani (Mart) Sacc, from wil- 

 ted upines, and F. orthoceras A. & W., from wilted asters. 



2. These species, and in addition, F. martii phaseoli Burk. F. conglutinans 

 Woll. and another strain of F. orthoceras A. & W., have been studied in culture, 

 to determine the effect of various media. The temperature, and the H-ion concen- 

 tration of the medium on the various growth charactex's. 



3. The type of growth varies on different media from a complete absence 

 (F. orthoceras on iris leaf juice agar) to a profuse production of aerial mycelium 

 (F. solani on Richard's solution). 



4. The colouration vaiies both in intensity and in the actual coloui pro- 

 duced. 



5. The production of chlamydospores appears to be related to poor nutri- 

 tion and is characteristic of such media as Harshberger's solution agar and the 

 different sugar agars. 



6. The type and proportion of conidia present and the size of the macro- 

 conidia present appear to very about a more or less constant mean. 



7. The total amount of fungous growth is greater at 25''c than at 20 c on 

 ischinsky's solution for all the species studied. 



8. More intense colours are usually produced at the higher temperature. 



9. The spore size is only slightly and not constantly influenced by the tem- 

 perature. 



10. The production of aerial growth is usually greater at 25 c that an 20 c 

 but again this is not constant, differing both with the organism and with the 

 medium. 



11. Some organisms show a gradation of growth characters with vaiying 

 H-ion concentration on the same medium, e.g., F. lathijri, F. martii phaseoli 

 and F. gibbosum. On the other hand, F. orthoceras (both strains) does not show 

 this gradation . It appears, therefore, that the H-ion concentration of the 

 medium is not the only factor affecting growth characteristics. 



