4 Synopsis of the Bacteria and Yeast Fungi. 



disarticulates itself from the barren part of the cell, which 

 then perishes, and the mature spore remains behind. These 

 spores possess the power of enduring adverse influences of 

 various kinds without injury to their vitality. They can 

 remain a long time in the ground, and then years after 

 proceed with their development ; they can also germinate 

 at once. At germination the spore first loses its brilliancy, 

 and swells up somewhat ; then the membrane of the spore 

 bursts in the middle. The inner part of the spore projects 

 through the opening, and grows to a new rod, the base of 

 which is sheathed by the split membrane, which is often not 

 thrown off for some time. 



When we attempt to define the genera and species of 

 the Schizomycetes, as we are wont to do with other 

 plants, we encounter great diflSculties, which must first be 

 shortly mentioned. The question is — What, in these Fungi, 

 is to be considered a genus and a species ? 



That there exist a number of different genera, i.e. 

 gfoups of distinct forms, in the Schizomycetes, is almost 

 universally admitted. But there are two opposed views con- 

 cerning the limitation of these genera. Naegeli recognises 

 only a few very variable groups of forms, while Cohn 

 establishes a whole series of genera, which he sharply 

 distinguishes, and which he divides into numerous species. 

 To me it seems very probable that several really distinct 

 and constant genera exist, e.g. Micrococcus (in an extended 

 sense), Bacillus, Spirillum, and Sarcina; while others of Cohn's 

 genera are only stages of development. I should decidedly 

 allow that the number of species is far smaller than one 

 would judge from Cohn's classification. For many of these 

 species are very probably only forms which have been 

 differentiated by the influence of various external agencies, 

 and have .become more or less constant. 



