SPORE-FORMATION. 63 



fission, give to the bundles of cells the appearance com- 

 monly ascribed to them, viz., that of a bale of cotton or 

 a packet of rags. (See Fig. 2, e.) 



The mode of multiplication of bacilli is similar to 

 that of the micrococci i. e., a dividing cell elongates 

 slightly in the direction of its long axis ; an indenta- 

 tion appears about midway between its poles, and 

 this becomes deeper and deeper, until eventually two 

 daughter-cells have formed. This process may occur 

 in such a way that the two young bacilli adhere 

 together by their adjacent ends in much the same way 

 that sausages are seen to be held together in strings 

 (Fig. 3,/), or the segmentation may take place more 

 at right angles to the long axis, so that the proximal 

 ends of the young cells are flattened, while the distal 

 extremities may be rounded or slightly pointed (Fig. 

 3, e). The segmentation of the anthrax bacillus, with 

 which we are to become acquainted later, results, when 

 completed, in an indentation of the adjacent extrem- 

 ities of the young segments, so that by the aid of 

 high magnifying powers these surfaces are seen to be 

 actually concave. Bacilli never divide longitudinally. 



SPORE-FORMATION. With the spore-forming bacilli, 

 under favorable conditions of nutrition and temperature, 

 the same mode of segmentation is seen to occur during 

 vegetation ; but as soon as these conditions become 

 altered by ilie exhaustion of nourishment, the presence 

 of detrimental substances, unfavorable temperatures, etc., 

 they enter, in their life-cycle, the stage to which we 

 have referred as spore-formation. This is the process 

 by which the organisms are enabled to enter a state in 

 which they resist deleterious influences to a much higher 

 degree than is possible for them when in the growing or 

 vegetative condition. 



