PARASITIC FUNGL 



the question as to their origin ; and he concludes that 

 endophytes are not produced from the metamorphosed 

 substance of diseased plants, but that they originate from 

 germs which penetrate healthy plants and develop a 

 mycelium. In the course of his investigations he notices- 

 the occurrence in the genus Cystopus of organs similar to 

 those long since discovered by Tulasne in Peronospora^ 

 which have been called OogonicC. He observes that rami- 

 fications perform the functions of antheridia, or male? 

 organs; and he proceeds to describe the production by th 

 oospores (or impregnated contents of the oogonia) of active 

 zoospores, similar to those produced by the ordinary spores 

 of Cystopus. Dr. De Bary states that these zoospores, after 

 remaining active for three or four hours, lose their cilia and 

 power of motion, assume a cellulose covering, and ger- 

 minate. He adds that the germ-filaments enter readily 

 by the stomates and leaves of the nutrient plant, but tha 

 those filaments only become developed which enter ths 

 stomates of cotyledons. In Peronospora the development 

 of the antheridia, oogonia, and oospores is said by De Bary 

 to be the same as in Cystopus; and he gives particulars of 

 the mode of germination of the conidia, and remarks on. 

 the growth of the parasite, which may be profitably 

 studied in the paper itself. 



Parasitic fungi, vegetable blights as they are commonly, 

 called, have of late years become objects of earnest atten- 

 tion, on account both of the enormous damage done to our 

 growing crops, and also of the many curious facts in their: 

 history which have been brought to light. Corn-blights 

 consist chiefly of mildew, Puccinia, smut, bunt, rust, 03? 

 red-robin, Uredo. Oidium is a common mildew ; Bo- 

 trytis another; jEcidiurn, forms a kind of rust infecting 

 pear-trees, the peridia of which form a very pretty object 

 for the microscope. (Plate I. No. 22, jEcidium Herberidis.)- 

 In the full-grown condition they appear as little cups filled 

 with reddish-brown powder (spores), and may be detected in 

 their earliest stages by the deformities they produce hi the 

 structure of the plants infested, or by pale or reddish spots 

 on the green surface, arising from the presence of the 

 fungus beneath. They are common on the coltsfoot, the 

 berberry, gooseberry, buckthorn, nettle, &c. Plate I. No. 19^. 



