SAPROPHYTES AND PARASITES 



which soon fall away. The germination of teleutosporcs 

 results therefore in a proniyceliuni, which develops small 

 secondary or promycelial spores, and these latter are ready to 

 germinate at once. \\'\\v\\ these promycelial spores are placed 

 on the damp surface uf the leaves of the host-plant they 

 germinate, and the growing point enters one of the stomata, 

 where it forms a mycelium, the contents of the promycelial 

 spore passing down the tube, whilst the empty spore-case soon 

 falls away. This new mycelium may produce spermogonia 

 and aceidiospores, thus reverting to the original point of 

 departure ; or it may give rise to a crop of uredospores, 

 without the intervention of aecidiospores ; or it may pro- 

 duce teleutospores, which are functionally alike or unlike 

 the parental teleutospores from which tlie promycelium was 

 derived. Throughout all these mutations there is no diver- 

 gence from the endophytal character of tlie parasite, which is 

 of a peculiar and characteristic type. Here, then, we have in 

 brief the typical life-hist(jry of one of the Uredineae — the 

 teleutospores in some instances being unicellular, and then 

 Uromyces ; or bicellular, and then Puccinia ; or multiseptate, 

 and then Phragmidium ; tlie character of the teleutospore 

 determining the generic name to be applied to the cycle. 



There have from time to time been suggestions of hereditary 

 transmission in Uredinous infection, but as the frank accept- 

 ance of such a possibility would weaken the effects of such 

 results as are claimed to follow upon artificial cultivation, the 

 advocates of heteroecisni ignore as much as possible all sugges- 

 tions of hereditary transmission. Analogy nevertheless favours 

 the probability of inheritance, and some few stubborn facts 

 seem to support this view. Some years since we had occasion 

 to examine some celery plants, the leaves of which were badly 

 attacked by Puccinia, whilst other plants in the same garden 

 did not show a single diseased leaf Upon inquiry it was 

 found that the diseased plants were raised from seed which 

 had been derived from plants badly diseased at the time, but 

 that the healthy plants were reared from seed which had been 

 saved from plants without trace of disease, either in the past 

 year or in their progenitors of preceding years. The foliage of 

 all the diseased plants was destroyed, and no disease appeared 



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