IIO BACTERIOLOGY. 



The belief is nevertheless rapidly gaining ground 

 that the lowest forms of vegetable life cannot be 

 divided by a hard and fast line into a series with 

 chlorophyll (Alga}, and a series without it (Fungi), 

 and the tendency now is to solve the difference of 

 opinion between Cohn and Nageli by following the 

 example of Sachs, and amalgamating the two 

 series into one group, the Thallophytes. 



Researches by competent observers have quite 

 recently clearly demonstrated that several micro- 

 organisms in their life cycle exhibit successively 

 the shapes characteristic of the orders of Cohn. 

 This had as early as 1873 been observed by Lister 

 in a bacterium in milk. Lister detected forms 

 of cocci, bacteria, bacilli, and streptothrix gene- 

 tically connected. Among the recent observers 

 Cienkowski and Neelsen have worked out the 

 different forms assumed by the bacillus of bhie 

 milk ; Zopf. has in a similar manner investigated 

 Cladothrix, Beggiatoa, and Crenothrix, and traced 

 out various forms ; Van Tieghem has investigated 

 Bacillus amylobacter with a similar result ; Klein 

 and others have met with an involution-form of 

 the filamentous growth of Bacillus anthracis; 

 Hauser has quite recently described bacillar, 

 spirillar, and spirulinar, and various other forms 

 in the Proteus mirabilis and Proteus vulgaris. 

 These facts obviously shake the very foundation 

 of Cohn's classification, and we are left without 

 possessing a sound basis for classification into 



