9 2 



CLASSIFICATION OF THE BACTERIA. 



covered pathogenic Spirobacillus Gierikowskii (of Daphnia magna) ; 

 and in 1892 by F. FISCHEL (I.) for Bacillus tuberculosis. It may 

 be remarked en passant, that Metschnikoff prefaced the report of 

 his discoveries with a short review (well worthy of perusal) of the 

 development of the pleomorphism theory. 



At the end of the " seventies " Cohn had established beyond 

 doubt the ability of certain fission fungi to produce endospores, 

 and thereby obtained reliable means of differentiation. Very 

 soon after, De Bary showed that several of the species which do 

 not form endospores protect themselves from injurious influences- 

 in another way, viz., by the formation of arthrospores. Hence a 

 classification was devised in 1883 by VAN TIEGHEM (II.), which 

 was further developed by DE BARY (I.) and HUEPPE (II.), in 



B 



FIG. 31. Bacterium Zoptii, Kurth. 

 Gradual changes in the same thread observed under the microscope. 



[A, thread without apparent articulation ; B, breaking up into rods which finally form 

 cocci in C ; a-e are corresponding cells. (After Kurth.) Magn. 740. 



1886, and in which two main groups were recognised, viz., the endo- 

 spore- and arthrospore-forming bacteria. The second group also 

 comprises all the species in which the formation of reproductive cells 

 has not yet been observed. Fuller details of this system can be seen 

 in Hueppe's treatise, but the system need not be further developed 

 here, as it has not yet been generally accepted in scientific circles. 



For fuller information regarding Van Tieghem's system, as well 

 as for particulars relative to the systems proposed by P. Miquel 

 and by Woodhead in 1891, which may be properly designated as 

 " diagnostic tables," reference may be made to WARD'S (III.) readily 

 accessible and comprehensive treatise. The new system published 

 by W. MIGULA (II.) in 1896 may also be simply referred to. 



In this connection there remains only one remark to be made, 

 and this concerns the term Bacillus. This word has been hitherto 



