The knowledge already won on the one hand by Tulasne, concerning the f ructificative 

 germination of the smut spores, and Kuhn's discoveries on the other hand, concerning the manner 

 of infection of the host plants by the smut germs, were supplemented so simply and naturally that 

 it became easy for the imagination to form a complete picture of the etiology of smut diseases. 

 Smut spores, germinating fructificatively in the earth, press, with the help of the conidia formed, 

 into the germinating seedlings and produce the smut diseases which appear first with the com- 

 pleted development of the host plants. 



From the discoveries already existing, scarcely a gap remained for further and new points 

 of attack in order to continue the investigations of smut diseases, and thus it becomes clear, that 

 the advancing understanding of the matter could reach a standstill as has been emphasized 

 already. 



My investigations begin here ; I began my observations by investigating the germination 

 of tj^'e sjjores of various smut fungi as far as they were accessible. In those investigations, I 

 had always to convince myself of the striking fact that the germination of smut spores is scanty 

 and inactive in water. As a rule, only a part of the spores germinate and the products of this 

 germination, the conidia of the promycelia, were so passive in their further germination that ger- 

 mination tubes were only rarely formed from them. Besides this, spores of other forms of 

 smut fungi behaved very negatively. They could not be brought to any germination in water ; 

 for example, the spores of the prevalent maize smut, which until then no one had seen germi- 

 nate. In the face of these phenomena of germination, the question was asked involuntarily, 

 how it was possible for these delicate germinating smut spores to reach the host plants and to 

 penetrate into them. This question became still more difficult when extended to the spores which 

 would not germinate at all, such as maize smut spores. 



These ever returning phenomena in the germination of spores in water pointed with urgent 

 necessity to the fact that a gap in our knowledge must exist at this place and that without the 

 co-operation of further, as yet unknown, factors for the germination and development of smut 

 spores, the existence of smut fungi and smut diseases could scarcely be thought possible in such 

 general distribution as we see them in nature. 



The developmental stages then suspected but still unknown, were found yery quickly when 

 I investigated the germination of the spores in nutrient solutions and substrata, instead of in 

 water. I had already carried this through successfully for a number of other fungi living para- 

 sitically 1 . It became evident first of all that the spores, otherwise germinating singly, were 

 stimulated at once to germination as a whole and that the smut spores which did not germinate 

 at all in water, such as the spores of maize smut, proceeded at once to germination, without an 

 exception. The development in nutrient solutions was as luxuriant as could be observed only 

 in other fungi living saprophytically. Who would have thought, in glancing at the abundant sapro- 

 phytic development, that developmental members of the most specific of all parasites were involved 

 here, which as yet had been observed only in definite species on living plants, and indeed only in 

 definite parts of those. 



(1) Compare the works published In Part IV of this work. 



