50 PUCCINIA MALVACEA.RUM 



of I'. Malvacearum is well known, though not usually interpreted 

 in that way, see Fig. 29.) These " end-conidia " do not form a 

 short tube, to penetrate t he cuticle of the host, but " pour forth 

 their protoplasm, as it seems, without the formation of an 

 opening, through the plasina-eonneetious of the outer wall of 

 the epidermis of the host into an epidermal cell," and so into 

 the tissues where it vegetates till required. It also exists in 

 the same state in the seeds of the infected plants. The fungus, 

 he says, "passes from the plasmatic into the filamentous state 

 just before the outbreak of the primary pustules." It is clear, 

 however, that the figures he gives do not prove what he asserts. 



Putting aside this purely supposititious and intangible 

 method, the chief means of perennation probably lies in the 

 fact that certain teleutospores produced at the end of the 

 growing season have the power of lasting through the winter 

 and germinating in the spring. Plowright, Massee and Tau- 

 benhaus all agree in this: the latter (1911) kept infected 

 leaves, gathered at Cornell University in the United States 

 from the living plant on November 26th, both indoors at a low 

 temperature and outdoors, and by testing spores taken from 

 them at intervals from December to April found that they still 

 remained germinable, though more and more slowly as time 

 went on. 



Dandeno, however (9th Report Mich. Acad. Sci. 1907, p. 68), 

 states that the fungus does not winter in the seeds ; he tried 

 seeds of diseased plants, carefully excluding infection from 

 outside, and found that they all produced healthy plants. His 

 experience also was that no teleutospores remained viable till 

 the next spring, but that the fungus maintained itself the 

 whole winter through on mallow plants in sheltered spots. 



These differences may be partly a matter of climate, and as 

 regards the " seeds," unless there were sori on them, they could 

 hardly be supposed to carry the infection, even if they came 

 from infected plants, except by the presence of " mycoplasm " 

 or mycelium, neither of which has been proved. 



For this reason the chief means of preventing the disease 

 (apart from using " seed " from uninfected plants) must be to 

 gather and burn all dead leaves from the infested bed. When 



