MOEPHOLOGICAL VARIETY OF BACILLUS ANTHRACIS. 265 



Note on the Foregoing, 



By 



E. Ray liankester, M.A., F.R.S. 



My friend, Dr. Klein, kindly suggests that I should add to 

 his paper a note calling the reader's attention to the series of 

 varieties of Bacterium rubescens which were described and 

 figured by me in vol. xiii, p. 408 (1873), and in vol. xvi, p. 27 

 (1876) of this Journal, since they offer an interesting parallel 

 to the important fact discovered by Dr. Klein. 



Dr. Klein's observation establishes that Bacillus anthracis 

 is, so far as form is concerned, a " Protean species," and once 

 for all demonstrates the error of those who, like Koch, have 

 arrived at the conclusion that the forms of Bacteriacese are 

 fixed and breed true. 



I have enumerated in the papers above referred to the pos- 

 sible variations of form known at that date as occurring amongst 

 Bacteriacese. The particular variety of Bacillus anthracis 

 now described by Dr. Klein adds a new form to the list there 

 given. 



Using the term " plastid " to denominate the unit of struc- 

 ture of the Bacteriaceae, I have pointed out four categories 

 under which their form-characlers may be grouped, viz.: 



A. Shape of the plastids. 



B. Substance of the plastid ; relation of protoplasm and cell 

 wall in each plastid. 



c. Distribution of colour (when present) in each plastid. 



D. Mode of aggregation of the plastids. 



Under heading a we have the following possibilities : 

 1. Spherical; 2. Biscuit-shaped; 3. Bacillar; 4. Filamen- 

 tous; 5. Acicular; 6. Serpentine; 7. Spiral; 8. Helicoid. 



Under heading b we have as possibilities — 



1. Plastids clean; or, on the other hand, 



2. Plastids gloeogenous (producing a jelly-like cell wall) 



