102 MORPHOLOGY AND CULTURE OF MICROORGANISMS 



corpuscles appear at the beginning of development in the form of very 

 small grains, which generally increase gradually in size during de- 

 velopment, and finally are absorbed in the very old cells. They are 

 sometimes distributed through the whole cell (Spirillum volutans) as 

 grains of chroma tin (Fig. 79, 8 and 9), but most often they tend to 

 gather at the two poles of the cell, or line up all along the bacillus 

 (Fig. 79, i to 4, 6, 10, n). In some species (B. alvei, asterosporus, 

 Bad. tuberculosis and diphtheria), these corpuscles grow bigger until 

 they attain relatively large dimensions, surpassing the bacillus in size. 



Thus they cause a series of swellings all 

 *; >; ;. ; * along the bacillus, which in consequence 



* * ' $ appears somewhat like a necklace (Fig. 

 79, n). They then give the illusion of 

 spores; one can easily understand the 

 error of some authors who have confused 

 them with spores, notably in the case of 

 5 9 "10 /%* the Bact. tuberculosis. 



In B. asterosporus, the metachromatic 

 FIG. 70. Various bacteria i -n i 



stained by a method which corpuscles usually appear in the youngest 



differentiates only the meta- cells, singly and in the shape of a small 



chromatic corpuscles. 1-4, -, 111 i_v 



Bacillus radicosus. 5-6, Bacil- central granule closely resembling a nu- 



lus asterosporus. 7, The same, cleus and which A. Meyer seems to have 



The cells have formed their , , f > /- \ 



spore and the metachromatic taken for such ( Fl S 79, S)- 



corpuscles outside of the spores During sporulation, the metachromatic 



have not yet been absorbed by i . , j r ,1 



it. 8-9, Spirillum wlutans. corpuscles exist just outside of the spore 



lo-u, Bacillus ahei. (Fig. 79, 7), then are finally absorbed by it. 



They therefore act like reserve products. 



Moreover, in the cells of bacteria other reserve products, notably 

 globules of fat and of glycogen, have been found. 



BACTERIAL CELL WALL. General Structure* All the bacteria have 

 cell walls and it is these that give definite form to the cell. These walls 

 are rigid and elastic and are probably made up of two layers, the outer one 

 of which is able to deliquesce and form capsules, or perhaps zooglosa. 

 The inner part retains the elasticity and gives the form to the bacteria. 

 These cell walls are readily permeable to water and it is through 

 them that all of the nourishment of the cell is obtained; that is, 

 there are no openings for the entrance of food or the discharge of 



Prepared by W. D. Frost. 



