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tecia. It is so common throughout central and eastern regions early in 

 the season, as well as later, that the idea of any seasonal migration from 

 its region of possible secia is clearly absurd. It must pass the winter in the 

 uredinial stage, and it probably does so as mycelium in the leaves of the 

 host. We have here a case of a rust which certainly maintains itself in a 

 fair state of vigor for some years without the intervention of recia and 

 probably maintains itself indefinitely. Of course it is possible that it is 

 constantly being renewed in vigor in the west by the presence of the secia, 

 and that the fungus thus renewed in vigor is slowly but continuously 

 migrating eastward; but such a hypothesis strikes one as being fanciful 

 rather than likely to be true. 



Puccinia Sorghi, the corn rust, is another species with a wide distri- 

 bution. It is usually not difficult to collect in any field of corn after tassel- 

 ing time. The infection is usually not heavy, however. The recia occur on 

 Oxalis, but they occur so seldom that they seem to have little to do with the 

 actual propagation of the rust. It is probably carried over from one year 

 to the next by urediniospores which survive the winter or by the uredinial 

 stage in living plants in southern regions. The latter source of infection 

 seems more likely for this rust than for wheat rust because of its later 

 appearance and less severity. 



Puccinia Asperifolii, the leaf rust of rye, is a rust which has no known 

 recia in this country. Its case in America is therefore comparable with that 

 of the bluegrass rust in this region or of P. graminis in Australia. It has to 

 maintain itself by the sporophytic stage only. 



Uromyces caryophyllinus on carnation is another rust which has no 

 recia in this country. There is no direct evidence that it can maintain 

 itself over winter, for it usually appears in greenhouses ; but it must have 

 passed through thousands of uredinial generations since it was introduced, 

 yet it seems to show no particular loss of vigor. 



Puccinia Chrysanthemi is a Japanese species which has been introduced 

 into America and Europe. It attacks cultivated chrysanthemums, chiefly 

 in greenhouses. It has now been known in this country for about a decade 

 and a half, and during this time it has never, so far as is known, produced 

 a teliospore, although in northern Japan and in the mountains of Japan 

 they are common. During this time no great impairment of vigor seems to 

 have taken place, although chysanthemum growers are able to keep it in 

 check by the use of resistant varieties and by the exercise of care in 

 watering. 



15—4966 



