214 Morphology and Systematic Botany under [BOOKI. 



observed these occurrences in 1858 in the case of an unusually 

 simple water-fungus (Pythium). De Bary showed that the 

 intrusive parasite vegetates inside the plant or animal which is 

 its host, and afterwards sends out its organs of propagation 

 into the open air, and that at a given time the organism 

 attacked by the fungus sickens or dies. These investigations 

 were not only of high scientific interest to the biologist, but 

 . they produced a series of results of the greatest importance to 

 agriculture and forestry, and even to medicine. 



With the Fungi, even more than with the Algae, the chief 

 difficulty in making out a complete series of developments in 

 the history of each species arose from the frequent intercalation 

 of the asexual mode of multiplication into the course of its 

 development, and in the further peculiarity, that the several 

 stages of development in some cases could only be completed 

 on different substrata. One of the most important tasks was 

 to find the sexual organs, the existence of which was rendered 

 probable by various analogies, and after De Bary had observed 

 the sexual organs in the Peronosporeae in 1861, he succeeded 

 in 1863 in proving for the first time that the whole fruit-body 

 of an Ascomycete is itself the product of a sexual act, which 

 takes place on the threads of the mycelium. 



The literature of mycology based on De Bary's methods of 

 observation and its actual results has been enriched by others 

 also in various directions since 1860 ; in the case of the Fungi, 

 as in that of the Algae, it is not possible yet to see to what 

 results investigation will ultimately lead ; but it is one of the 

 fairest fruits of strictly inductive method, that it has succeeded 

 in smoothing this thorny and indeed perilous route, where the 

 enquirer is constantly in danger of being misled, and in satisfy- 

 ing the severest demands of science. Conclusions have been 

 already reached that are important for morphology and syste- 

 matic botany, and among these the establishment of the nature 

 of the large sporophores, and of processes similar to the 

 alternation of generations in the higher Cryptogams should be 



