52 BACTERIOLOGY. 



Owing to the peculiarly dense character of the spore- 

 wall the anilin dyes do not readily stain the spore. On 

 staining, therefore, it appears as a colorless body imbedded 

 in a stained cell, or rather within the stained cell-wall. 

 The ^presence of a bright, refracting body within an 

 unstained cell, or the presence of a colorless, non-staining 

 body in a stained cell does not prove that it is a spore. 

 Such spore-like bodies, which may be termed pseudo-spores, 

 have been frequently observed, and mistaken for spores. 

 Thus, the so-called spores of the tubercle bacillus are due 

 to differences in the density of the protoplasm which con- 

 tracts into beads or balls, thus leaving vacuoles or clear 

 spaces filled with a cell fluid. The small bright polar 

 bodies which are frequently seen in glanders, diphtheria, 

 typhoid and other bacilli are to be considered as small 

 masses of condensed protoplasm since they stain more 

 deeply than the surrounding contents. The resistance to 

 destruction is a valuable criterion of a spore-like body, but 

 even this does not prove its spore character. The true 

 character of a spore can only be established by observing 

 its germination. 



Spore germination. — The spore which is formed in a given 

 culture medium does not germinate until after it has been 

 transplanted to a good new soil. The original medium is 

 unfit for this purpose largely because of the presence of 

 various chemical products, which were elaborated by the 

 vegetating or growing organisms. Moreover, it was the 

 presence of these products which stimulated the cells to 

 form spores. In a suitable soil, and under proper condi- 

 tions, the spore gives rise to a young, growing cell, which 

 rapidly increases in size, reaches \^hat may be called the 

 adult state, and multiplies. Eventually, this progeny of 

 vegetating cells gives rise to new spores. 



Like the seed of higher plants, the spore itself does not 

 multiply. Under no condition will one spore divide ahd give 



