194 IMPORTANT VARIETIES OF FISSION-FUNGI. 



(compare p. 124), sometimes forming long true or ap- 

 parent threads, with or without flagella. Always with- 

 out endospores; 1 in single varieties arthrospores are de- 

 scribed. 



Many hundred spore-free, short rods have been de- 

 scribed, and the need of arranging them in a natural sys- 

 tem, founded entirely upon morphologic peculiarities, 

 was strongly felt. The only characteristic which is ques- 

 tionable is that of flagella, and we acknowledge that the 

 system founded by A. Fischer and Migula upon the 

 flagella appealed to us very favorably until we had our- 

 selves worked extensively with the staining of flagella. The 

 results of these extensive and careful studies were unfor- 

 tunately not of such a nature as to allow a classification 

 founded upon the number and arrangement of the flagella 

 to appear practical. Especially the statements in the 

 literature regarding flagella are often inexact, and a num- 

 ber of inaccessible varieties could not be classified at all. 

 At times we observed that closely related varieties, as in 

 the colon group, occur which have either one flagellum or 

 many or no flagella. What appeared yet worse was that, 

 as in Bacterium violaceum, we found one form with 

 flagella on all sides ; another with only one or with one 

 polar and one lateral flagellum. Migula found it to have 

 one polar flagellum. 



In addition, there are the experiences which we have 

 encountered regarding the permanent loss of flagella in 

 Micrococcus agilis Ali-Cohen, Micrococcus agilis Menge, 

 and Sarcina mobilis, and regarding the acquiring of motil- 

 ity by the Bacillus implexus, and reported in this book. 

 If we ourselves have not observed similar occurrences in 

 any bacterium, we find the statement made by Germano 

 and Maurea, that they have twice seen non-motile cultures 

 of the typhoid bacterium. 



Finally, we feared to scare the beginner from making 



1 Upon ordinary media (bouillon, gelatin, agar, potato) these varie- 

 ties never possess spores. As already remarked, we were also unable 

 (with a doubtful exception in the Bact. violaceum) to observe spore- 

 formation upon quince and marshmallow decoction in those previously 

 considered as not forming spores. Migula seems to have been more 

 fortunate, but gives no particulars. 



