48 THE LARCH CANKER 
TABLE SHOWING RATES OF GROWTH OF 
After Eighteen hours. Forty-three 
Average 
length 
Number | of those | Number 
Longest. | measured.| measured. | Remarks. | Longest. | measured. 
Cultures A,-A, 35 uw —_ _ Very few 238 pw 19 
Temp. 13°-14° C. germina- 
ting 
Cultures A,-A, 165 p ll 138,» | Very 490 p 7 
Temp. 22°-23° C. many 
germi- 
nating 
Cultures A,-A,» 132 p 22 9ly | Very 194 p 17 
Temp. 26°-27° C, many 
germi- 
nating 
In agar-agar cultures numerous spermogonia were formed 
after a few months. These spermogonia were somewhat 
larger than those found on larch trees and, but for their 
apices, were sunk in the substratum. They produced 
normal spermatia which resisted all my efforts to germinate 
them. No such spermogonia were formed in gelatine 
cultures. 
Cultures on other media may be obtained directly from 
spores, but on the whole it is easier to start from the my- 
celium growing on gelatine or agar-agar. In this way 
cultures have been grown on moistened sterilized bread 
cubes in Erlenmeyer flasks and on pieces of branches of 
European and Japanese larch which have been sterilized in 
steam. On these larch stems apothecia were developed 
completing the life-cycle from spore to spore (fig. 23) ; there 
is no difference between such cultures obtained from the 
parasitic or saprophytic form of the fungus. 
Mycelial cultures were also grown successfully on sterilized 
