MICHIGAN ACADEMY OF SCIENCE. 



69 



might pass the winter in the myceHum embedded in the embryo of the seed, 

 and when the embryo began to grow, the fungus might be expected to grow 

 with it. Following this suggestion, many affected seeds were collected and 

 planted, then kept under conditions imfavorable to inoculation from external 

 sources, but in no case did the rust appear on seedlings grown from affected 

 seeds. It is stated Iw ^lassee that it often passes the winter thus, i. e., in the 

 embryo of the affected seed, but this was not borne out 1)y the experiments 

 in connection with this paper. 



Massee also states that the teleutospores i^roduced late in the season 

 acting as resting spores, and then germinate in spring, thus tiding the fungus 

 over winter. A number of observations and tests were made to sustain, if 

 possible, this view, but without success. Very favorable conditions ren- 

 dered a minute study of this point comparatively easy. There w^as an im- 

 mense plot of mallows quite near the laboratory, and these were every year 

 badly infested with the rust. It Avas so aljundant, and the mallows so large 

 and luxuriant, that material could always be obtained throughout the winter. 

 Many of the plants wintered as perennials, so that it was possible to get living 



tissue at any time. None of the old spores could be got to germinate. In 

 fact most of them had germinated and nothing remained but the walls of 

 the old teleutospores. Those which had not germinated seemed dead. 

 These were the latest of the season and should, according to Massee, germi- 

 nate, but they did not. An extra effort was made in early spring to secure 

 some which would germinate, because at this time of the year the teleutospores 

 of many other species of rust send out a germ tube quite readily. None of 

 the mallow rust showed any signs of life, although they are unusually favor- 

 able forms for the illustration of sporidia production. The idea of teleuto- 

 spores wintering over had to be abandoned. "^ One attempt among many 

 might be mentioned to show^ that teleutospores did not survive the winter. 

 A large amount of dead^leaves and stems^ of _ affected mallows containing 

 countless numbers of teleutospores were strewn the following spring among 



