278 BACTERIOLOGY. 



In the slip stained by the Gram method the same 

 groups of the cocci which grow as threes and fours will 

 be seen, but our lancet-shaped diplococci will now pre- 

 sent an altered appearance there can now be detected 

 a capsule surrounding them. This capsule is very deli- 

 cate in structure, and, though a frequent accompani- 

 ment, is not constant. It can sometimes be demon- 

 strated by the ordinary methods of staining, though 

 the method of Gram is most satisfactory. (Fig. 62.) 



In the third slip which has been stained by the 

 method given for tubercle bacilli in sputum, if decol- 

 orization has been properly conducted and no contrast- 

 stain has been employed, the field will be colorless or 

 of only a very pale rose color. None of the numerous 

 organisms seen in the first slip can now be detected, but 

 instead there will be seen scattered through the field 

 very delicate stained rods, which present, in most in- 

 stances, a conspicuous beaded arrangement of their pro- 

 toplasm that is, the staining is not homogeneous, but 

 at tolerably regular intervals along each rod there are 

 seen alternating intervals of light and color. These rods 

 may be found singly, in groups of twos and threes, or 

 sometimes in clumps consisting of large numbers. 

 When in twos or threes it is not uncommon to find 

 them describing an X or a V in their mode of arrange- 

 ment, or again they will be seen lying parallel the one 

 to the other. 



If contrast-stains are used, these rods will be detected 

 and recognized by their retaining the original color with 

 which they have been stained, whereas all other bacteria 

 in the preparation, as well as the tissue-cells which are 

 in the sputum, wil 1 take u p the contrast-color. (Fig. 61.) 



These delicate beaded rods are the bacillus tubercu- 



