F. J. F. SHAW. 



129 



Experiment T\ Cow pea (Pusa seed). 



Cross inoculations. 



Eriksson(ll) investigated the parasitism of Rhizoctonia oit 

 carrots, beet-root and other European hosts, and found that tlie 

 susceptibiKty of carrot to the attack of Bhizoctonia varied according 

 to the variety of carrot infected. He was able to make the Rhizoc- 

 tonia pass from the carrot to the beet. Its virulence upon beet, 

 however, was greatly increased after being parasitic upon that plant 

 for one generation, thus showing a gradual adaptation to the new 

 host ; clover, which is sometimes attacked in Denmark, he was not 

 able to infect with this Rhizoctonia. Eriksson's results show there- 

 fore a very slight speciahsation in the parasitism on different hosts. 



In the case of the four crops dealt with in this research the 

 results agree more or less with those of Eriksson. In three of the 

 hosts, namely, ground nut, cotton and cow pea the infection powers 

 of the respective Rhizoctonias seem to be of a like order. In each 

 case the fungus isolated from any one host will infect the other two, 



