STRUCTURE OF BACTERIAL PROTOPLASM. n 



portions in the bacterial protoplasm. In a bacillus or 

 spirillum there is often such a body at each end, in which 

 case they are frequently called polar granules (vide Fig. i, 

 No. 13) (German, Polkornchen or Polkorner). 



For the demonstration of the metachromatic granules two methods 

 have been advanced. Ernst recommends that a few drops of Loffler's 

 methylene-blue (vide p. 97) be placed on a cover-glass preparation 

 and the latter passed backwards and forwards over a Bunsen flame 

 for half a minute after steam begins to rise. The preparation is then 

 washed in water and counter-stained for one to two minutes in watery 

 Bismarck-brown. The granules are here stained blue, the protoplasm 

 brown. Neisser stains a similar preparation in warm carbol-fuchsin, 

 washes with I per cent sulphuric acid and counter-stains with Loffler's 

 blue. Here the granules are magenta, the protoplasm blue. The 

 general nature of the granules thus is that they retain the first stain 

 more intensely than the rest of the protoplasm. 



The polkornchen can be demonstrated by the fact that they rema 

 unstained when the bacteria are treated with any of the ordi 

 stains. 



Both the metachromatic granules and the polk6rn 

 have been looked upon by different observers as 

 Against this view, however, is the fact that growths in 

 they exist show no higher degree of resistance than growths 

 in which they cannot be observed. Further, they do not 

 react to the strict methods of spore staining. Some have 

 looked upon the metachromatic granules as evidences of 

 the process of division in the bacterial protoplasm, i.e., of 

 a kind of mitosis. If such is the case they ought to be 

 observed in some members of a growth where active 

 multiplication is going on, and this is not so. The con- 

 ditions in which they occur are in growths where the food 

 material is becoming exhausted, or in growths which have 

 been subjected to unfavourable conditions. Thus they 

 have been observed in bacteria which have been grown 

 for a few days at the most favourable temperature, and 

 thereafter allowed to develop further at less suitable 

 temperatures. It is thus very probable that the occurrence 

 of metachromatic granules in a bacterium indicates the 

 onset of degenerative changes. 



With regard to the polkorner we have seen that evidence 



