Host and Parasite in certain Diseases of Plants. 433 



Fig. 11. A young snowdrop plant, artificially infected with Botrytis. The infection- 

 spot (a) is sunken in the centre, and deep sienna brown or nearly black ; the 

 paler area around is yellowish -brown. The fungus hyphae extend from this 

 centre into the tissues, or not, according to circumstances. (See text.) 



the infecting mycelium, that I was continually puzzled to account for 

 the phenomena, and suspected that the conidia varied in infecting 

 power, according to their size as well as the manner of culture. This 

 would be a natural conclusion from what was already proved with 

 regard to the invigoration of the mycelium, for, after all, conidia are 

 only slightly specialised bits of mycelium cut off for purposes of rapid 

 propagation,* and we may expect them to be directly affected by 



* See Sachs, ' Lectures on Phys. of Plants,' p. 722 ; also de Bary's critical 

 remarks in ' Comp. Morph. and Biol, of Fungi,' p. 129. 



