STRUCTURE OF BACTERIAL PROTOPLASM 9 



of the higher bacteria, motility is probably due to contractility 

 of the protoplasm itself. 



The Minuter Structure of the Bacterial Protoplasm. Many attempts 

 have been made to obtain deeper information as to the structure of the 

 bacterial cell, and especially as to its behaviour in division. These 

 ha vi- largely turned on the interpretation to 1m put on certain appear- 

 ances which have been observed. These appearances are of two kinds. 

 First, under certain circumstances irregular deeply-stained grannies are 

 liM-m-d in the protoplasm, often, when they occur in a bacillus, giving 

 the latter the appearance of a short chain of cocci. They are often 

 called metachromatic granules (vide Fig. 1, No. 16) from the fact that 

 by appropriate procedure they can be stained with one dye, and the 

 protoplasm in which they lie with another ; sometimes, when a single 

 stain is used, such as methylene blue, they assume a slightly different 

 tint from the protoplasm. 



For the demonstration of the metachromatic granules two methods 

 have been advanced. Ernst recommends that a few drops of Lofflers 

 methylene blue (vide p. 104) 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 1 per cent, sulphuric acid, and counter-stains with Loffler's blue. 

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

 character of the granules thus is that they retain the first stain more 

 intensely than the rest of the protoplasm does. 



A second appearance which can sometimes be seen in specimens 

 stained in ordinary ways is the occurrence of a concentration of the 



Protoplasm at each end of a bacterium, indicated by these parts being 

 eeply stained. These deeply stained parts are sometimes called polar 

 granules (vide Fig. 1, No. 16, the bacillus most to the right) (German, 

 Polkiirnchen or Polkorner). 



With regard to the significance that is to be attached to such 

 appearances, much depends on whether they are constantly present 

 under all circumstances, or only occasionally, when the organism is 

 grown in special media or under special growth conditions. Some 

 bacteria, however stained, show evidence of having the protoplasm 

 somewhat granular, e.g. the diphtheria bacillus. In other cases this 

 granular condition is only seen when the organism has been grown under 

 bad conditions, or where the food supply is becoming exhausted. Some 

 have thought that the appearances might be due to a process allied to 

 mitosis and might signify approaching division, but of this there is no 

 evidence. 



In perfect healthy and young bacteria, appearances of granule 

 formation and of vacuolation may be accidentally produced by physical 

 means in the occurrence of what is known as pltumotyffa To speak 

 generally, when a mass of protoplasm surrounded by a fairly linn 

 envelope of a colloidal nature is placed in a solution containing salts in 

 greater concentration than that in which it has previously been living, 

 then by a process of osmosis the water held in the protoplasm passes 

 out through the membrane, and, the protoplasm retracting from the 

 latt- T, the appearance of vacuolation is presented. Now, in making a 



