ioo MICRO-ORGANISMS AND DISEASE. [CHAP. 



Any part of this pellicle examined under the microscope 

 shows itself to be a zooglcea in the true sense of the word, 

 vast numbers of shorter or longer bacilli crossing and inter- 

 lacing and lying embedded in a gelatinous hyaline matrix. 

 As with bacterium termo, one occasionally notices at the 

 margin of the mass one or other bacillus wriggling itself free 

 and darting away. And in the case of non-motile bacilli, 

 putrefactive and others, I have also seen distinct formations 

 of zooglcea, having the shape of spherical or oval lumps of 

 various sizes composed of a hyaline jelly-like matrix, in which 

 are embedded the bacilli in active multiplication. 



In those species in which the bacilli are capable of forming 

 leptothrix (leptothrix buccalis, hay-bacillus, anthrax-bacillus) 

 the filaments may form dense convolutions. When in these 

 convoluted filaments spores are formed (see below) and the 

 sheaths of the filaments swell up and become agglutinated 

 into a hyaline jelly-like substance, the spores appear to form 

 a sort of zooglcea. 



Bacilli are killed by drying, but it is necessary to bear in 

 mind that they must be exposed to the drying process in thin 

 layers (Koch). At the temperature of boiling water they are 

 invariably killed, but not their spores. Even heating them 

 from half an hour to several hours at a temperature above 

 55 or 60 C. kills them. Freezing also kills them, but not 

 their spores. Carbolic acid, corrosive sublimate, thymol, 

 &c., kill them. 



One of the most striking phenomena in the growth of 

 bacilli is their power of forming spores. These are generally 

 oval when fully developed, spherical when immature; they 

 are of a glistening appearance, and take the ordinary dyes 

 either with difficulty or not at all ; they are generally a little 

 thicker than the bacilli within which they have developed. 

 Their formation always takes place in this way : in one or 



