72 CLASSIFICATION OF THE BACTERIA 



brought to light, they then asserted pleomorphism to be peculiar to the non- 

 pathogenic bacteria. Even this restricted assumption has, however, given \vay, 

 since undoubted pleomorphism was proved in 1882 by ARCHANGELSKI (I.) and 

 ROLOFF (I.) for Bacillus anthracis, and by Friedlander for Pneumobacilhis ( 33) ; 

 in 1883 by TH. EHLERS (I.) for the Rauschbrand bacillus (of symptomatic 

 anthrax); in 1889 by E. METSCHNIKOFF (II.) for his newly discovered pathogenic 

 Spirobacillus Cienkowskii (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 



B 



FIG. 31. Bacterium Zopfii, Kurth. 



Gradual chaiigcs iu the same thread observed under the microscope. 



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



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



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 1886, and in which two main 

 groups were recognised, viz., the endospore and arthrospore forming bacteria. 

 The second group also comprises all the species in which the formation of repro- 

 duce! ve 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 parti- 

 culars 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, arid this 

 concerns the term Bacillus. This word has been hitherto employed by us to 

 designate only a well-defined form-phase of cell, viz., the cylindrical bacterial cell, 

 the length of which is at least double the breadth. Hueppe's system, however, 

 applies the generic name Bacillus only to such rods as have been proved capable 



