37& 

 relation to their v/eight, a surf ape area seventy tirces greater tMn that 

 of AscoholTis spores. The energy necessary to transport the ascospores is, 

 therefore, only one seventieth of that required to carry away the Ascotolus 

 spores, not taking into account at all the fact that they have only one- 

 five thousandth part of the weight of the latter. 



By numerous experiments, FalcS: showed that the above 

 factors are operative in the field. He proved that insects, iQiin, and 

 other cliiratic factors are not necessary for the infection of rye "by 

 Claviceps. He showed that as the temperature of the ground at any time is 

 higher tlian is that of the surrounding air, there ia always a constant 

 falling of temperature and, therefore, an air current viiich is sufficient 

 to carry the ejected spores to the heigjht of the heads, where under favorahle 

 climatic conditions, of moist air and quiet weather they will cause 

 infection. 



Me thod of infection 

 The exact method by which the fungus penetrates the ovary 

 is not loiown. It seems, ho^vever, quite evident that it does not penetrate 

 through the glumes, as indicated by the smaller degree of infection in 

 varieties of plants that have their glumes closed during the period of 

 flowering. Engelke found that infection was successful only before the 

 flovver was pollinated and before the pollen grain had sent out its germ tube. 

 At this stage the spore or oonidium that has found its way to the flower can 

 germinate in the nectar of the flower and then extends into the cavity of the 

 ovary around the ovule, v/here it begins the transfornation of the ovary by 

 the ?5reg4tive processes of the mycelia. This according to him,,' sxplainsthe 

 formation of the sclerotia in the place of the ovary instead cf at the base 

 of the Icernel as was supposed at first. Infection through the "spaltoffnungen 



