30 



I;I;A' THIN < IF HOST TO PARASITIC ATTACK. 



Still mure striking are certain structures resembling witches' 

 s, \vhich are produced on Thujopsis dolabrata in Japan, under 

 inHuence of the mycelium of Gacoma clef or mans (Fig. 8). 

 These consist of leafless non-chlorophyllous axes, dichotomously 

 branched, and with each branch ending in a disc. They arise 

 from shoots or leaves of the T/injjt*is where structures of the 

 kind would never have arisen normally, and are wholly sub- 

 servienl to the reproduction of the fungus, which forms its 

 i under the epidermis of the terminal discs. 



PIG. 8. Caeoma deformans. The nest-like structures are much-branched, 

 leafless shoots with each of their twigs ending in a caeoma-disc. (v. Tubeuf 

 phot.) 



Tin.; galls produced by Ustilago Treubii on Polygonum Saccha- 

 are particularly interesting. Here, as a result of the 

 l>!".sence of the parasite, there are formed the so-called vegetative 

 'anker-galls, and in addition, the fruit-galls, new organs derived 

 from lateral outgrowths of the host-plant, and of use only 

 in the spore-formation of the Ustilago; they contain a special 

 capillitium-like tissue, and serve exclusively for the shelter and 

 distribution of the fungus-spores. 



