88 Fermentation and Kindred Phenomena. 



method is very analogous to the ascosflore formation of yeast, 

 and is evidently a provision of Nature's for preventing the 

 organisms from becoming extinct under conditions unfavourable 

 for their ordinary life and development. In spore formation 

 the contents of the cell contract, and eventually a round spore 

 is produced within the cell, which finally escapes. The spore 

 placed under favourable conditions eventually germinates into 

 a mature organism. 



The resisting power of the spores to the action of agencies 

 fatal to the existence of the organism from which they were 

 developed, or into which they grow, is very striking, and fully 

 accounts for the difficulties experienced in disinfection, and also 

 for many of the mistakes which were made by the believers in 

 the doctrine of spontaneous generation in interpreting the 

 results of their experiments. Again and again they declared 

 that organisms made their appearance in liquids which had 

 been thoroughly freed from them. No doubt the organisms 

 themselves were absent, but their spores were present, not 

 having been destroyed during the preparation of the infusion. 

 Thus the bacillus of hay infusion may be boiled in water for 

 ten minutes without losing its vitality, and it may be soaked 

 in pure carbolic acid and in other strong disinfectants without 

 losing its power of germination. The resistance of these per- 

 manent spores to agencies which easily destroy the life of the 

 mature organisms with which they correspond is a point of 

 great importance with regard to infectious and contagious 

 diseases (or at least to some of them), but I hope to touch on 

 this matter later on. 



There is only one other consideration I shall mention in con- 

 nection with the morphology of the schizomycetes, but it is of 

 importance, and may considerably modify many of the present 

 views. It has been asserted again and again — and I think the 

 eminent surgeon Loeher was among the first to make the state- 

 ment — that certain of these organisms under special conditions 

 undergo a metamorphosis of such a kind that a micrococcus can 

 become a bacterium, the bacterium a bacillus, the bacillus a 

 leptothrix thread, or a spirillum, &c. ; in short, {hat in certain, 



