422 The Botanical Gazette. [September, 
dened condition that is found in the present genus Bacillus. 
The logical nature of this scheme is praiseworthy but the 
present necessities of our classification hardly warrant the 
formation of a number of genera for which there are noknown 
representatives. 
The fact that the author himself is forced to note under 
many of the genera that ‘‘bisjetzt ist kein Vertreter dieser 
Gattung bekannt” and also that under the genus Bactridium, 
“‘hierher scheinen eine gréssere Zahl von Stibchenbakterien 
zu gehoren” is evidence of the inherent weakness of the sys- 
te 
m. 
The difficulty of founding any system of classification upon 
a characteristic so difficult to determine with accuracy as the 
presence and arrangement of such delicate organs as the cilia 
of bacteria is apparent. Even with much simplified methods 
of staining, the study of these motile organs is not an easy 
task and when used as a basis for classification would cause 
more confusion than now exists. The author ignores com- 
pletely all reference to a similar system proposed by Messea® 
in 1891 which failed of acceptance on account of the many 
new difficulties that it introduced. Desirable as a system 
would be that is based on morphological data entirely, none 
has as yet been presented that is as convenient and practical 
as those that employ physiological characteristics in addition 
to the morphological variations of the cell.—H. L. RUSSELL. 
. - 7 i 
*Contribuzione allo studio delle ciglia dei batterii e proposta di una classifi- 
cazione. Rev. d’Igiene 1: —. 1891. [No. 14.] 
