TEXT-BOOK OF BACTERIOLOGY. 3 



tion of anthrax bacilli in the process of sporuiation, a very different 

 appearance from the above is developed, namely, roundish blue 

 grains, lying at regular distances from each other, and also a 

 single row of them surrounded by a light border (like a halo). 

 These anthrax spores before being stained are first strongly heated, 

 then stained, and afterward treated with a solution of iodine. Dif- 

 ferent methods of preparation may cause them to present dissimi- 

 lar appearances under the microscope. If we examine unstained 

 anthrax bacilli from a bouillon culture (with system 7, ocular 2) 

 long fibres will be seen which are perfectly uniform, and in which 

 even on close examination, no division into separate pieces can be 

 observed. 



If a preparation be treated with gentian-violet, we immediately 

 notice that the threads consist of a row of cells of equal length, 

 closely connected, and whose points of division had previously es- 

 caped observation. 



In fact, the investigation as to the true shape has caused the 

 greatest difficulty to the investigator. 



At this point let us consider some appearances which have raised 

 doubt in regard to the constancy of their form. 



If we employ a fluid preparation which has been made from 

 the liver tissue of a Guinea-pig whose death has resulted from in- 

 oculation with anthrax and stain it with aniJin-red (fuchsin), large 

 thick rods will be seen spread in rich profusion over the whole mi- 

 croscopic field of vision. If, on the other hand, we examine a sec- 

 tion from the liver of the same animal similarly treated with fuch- 

 sin, we shall find the bacilli present in as great numbers as before, 

 but they will appear much more slender and insignificant, scarcelj" 

 to be compared with the fine-looking specimens of the previous 

 preparation. This result is attributed to the alcohol in which the 

 organ had previously been hardened, for it contracts the tissues 

 and alters the appearance of the bacteria. 



Frequently, however, variations in form are due to other circum- 

 stances. The bacterium passes through a course of development 

 like plants of a higher order. It is young, it grows, reaches the 

 highest development, and then generates cells of the same kind. 

 It cannot, therefore, surprise us if young bacteria which have just 

 proceeded from others appear smaller, and if old bacteria which 

 are just about to divide appear larger than the average normal 

 cells. 



The circumstances of their nourishment exercise a very impor- 

 tant influence on the appearance of the bacteria. The degree of 

 perfection of their nutrition affects the vigor of their development. 



