186 DISEASES OF FIELD & GARDEN CROPS. [OH. 



Germinating spores of Uredo, Puccinia, and dEcidium tra- 

 verse the scratches made by a lancet on our glass slides just 

 as naturally as if they were the furrows of a leaf-cuticle. 

 When the threads get to the edge of the glasses they dip 

 down just as naturally as if the vacant space were an 

 open organ of transpiration. We have grown spores on 

 moist linen, calico, and blotting-paper, and the germ-tubes 

 have penetrated between the orifices and run over the 

 reverse side just as if they were in a leaf. Such spores, 

 unless of moulds, of course do not reproduce a perfect 

 fungus like the one from which they originally arose ; 

 neither do those sown on leaves. Professor De Bary says 

 he could not cause jEcidium spores to grow effectually on 

 barberry leaves. It is only after a considerable time ha.s 

 passed, and the germ-threads have been lost to sight for 

 many days, several weeks or months, that some new fungus 

 of an apparently different nature at length appears. 



One writer has said that botanists were prepared to 

 accept the idea of Puccinia and dScidium being one and 

 the same fungus because they were acquainted with the 

 changes of some insects such as are familiar in the cater- 

 pillar, chrysalis, and perfect butterfly in the insect world. 

 We confess that we do not see the resemblance at all, 

 No condition of the insect is ever lost to sight for ten or 

 twelve days or two months, and the change is gradual 

 throughout from one form to the other ; the chrysalis is 

 foreshadowed in the caterpillar, and the perfect butterfly 

 has all its parts in the chrysalis. No organisms belong- 

 ing to Puccinia are ever indicated by ^Ecidium, and no 

 analogues of Spermogones or ^Ecidiospores are ever met 

 with in Puccinia. 



It has been stated by Professor De Bary that an ana- 

 logous case of the change of host exists in the animal 

 kingdom, as in the case of the entozoic worms, which pass 

 the first part of their existence in one animal, and the 

 second part in another and totally different animal. The 

 experiments with entozoic animals have doubtlessly proved 



