CONSTANCY AND MUTABILITY OF FUNGI. 683 



In this case the attenuation would be analogous to the 

 numerous degenerative processes which have heen ob- 

 served in higher organisms ; the diminution in the 

 amount of quinine in the species of cinchona, the loss 

 of the production of conium in hemlock when the plants 

 are cultivated in unsuitable soil, the diminution in the 

 amount of chlorophyll, or the imperfect and slower 

 growth of the various organisms under unfavourable 

 external conditions, would then furnish analogous ex- 

 amples. 



But it is remarkable that the attenuated condition of An attenuated 

 pathogenic and fermentative bacteria cannot as a matter however? 1S 



of fact be removed, as in the case of these degenerated t 

 plants, by subsequent cultivation under normal condi- generations. 

 tions. On the contrary, undoubted facts have been 

 made out which show that this attenuated condition 

 can last for a long time, and through a long series 

 of generations, more especially when it was set up by 

 milder means, employed for a long time. 



Thus in the case of many bacteria a character has 

 been made out which must be regarded as a biological 

 curiosity, and which does not in any way harmonise 

 with the other biological characters of the bacteria. For Thus a 

 on the whole we undoubtedly observe, as has been stated chaSTr has 

 above, a constancy in the hereditary properties of the ^en P rov f^ 

 bacteria similar to that of the higher plants, and even the bacteria 

 the virulence of the parasitic bacteria appears to corre- Entirely ^rom 

 spond in its laws with those of the other characters, in ^ a j of the 



. ... . higher organ- 



that in spite of numerous variations in the cultivation, no isms. 

 alteration occurs, or only appears under certain abnormal 

 conditions, and then affects the one generation alone. 



There can, however, be no longer any doubt as to the 

 remarkable fact of the artificial development of a here- 

 ditary attenuated condition in some bacteria, and as the 

 result of this most recent development of our know- 

 ledge, we must come to the conclusion that we ought to 

 be extremely cautious in our judgment when we attempt 

 to apply laws which concern other organisms to bacteria, 

 or when we would draw general conclusions with regard 

 to bacteria from single observations. 



