MICEOCOCCJ PATHOGENIC IN THE LOWEE ANIMALS. 209 



cocci"; the organisms are also found iiithe eggs of the butter- 

 flies, and by means of these infected eggs the hereditary 

 transmission and the continuance of the disease is provided 

 for ; for otherwise, on account of the slight resisting power of 

 the micrococci, they would be in danger of disappearing. 

 Pasteur has demonstrated experimentally that the disease 

 may be transmitted by micrococci contained in the food, or 

 by their penetration through injured parts of the skin, and 

 that currents of air, handling by the breeder, &c., may lead to 

 the spread of the infective germs. As prophylactic means 

 the plan introduced by Pasteur is now generally adopted ; 

 the butterflies which are laying eggs are separated in pairs, 

 and after copulation and the laying of the eggs, are examined 

 as to the presence of the characteristic "micrococci." If 

 the latter are found the eggs are destroyed, and not employed 

 for breeding. 



To this group also belong some infective wound dis- Koch's micro- 



, , . , . , . , , p ,, cocci in the 



eases in animals which were investigated as fully as infective 



possible by Koch by microscopical observation at a time Jgea!se S of the 

 when no trustworthy methods of cultivation were known, lower animals. 



Micrococcus of Progressive Necrosis of tissue in Mice. 

 Round cells, 0*5 /*. in diameter,usuallyarrangedin beautiful 

 and regular chains, at times 

 massed together in thick 

 groups (fig. 52), causes ne- 

 crosis of the tissue ; as far 

 as the micrococci reack no 

 blood or connective tissue 

 cells remain intact, and even " ....... 



the cartilage cells are de- 



stroyed. The gangrene ex- Fig. 52. Micrpcocci of progressive 



tends from the point of SSSf" 



inoculation, and SOOn causes , cells of the cartilage of the ear. 

 death (in about 3 days); ^ ^hain forming micrococci. 



the blood and internal organs remain free from micro- 

 cocci. From their behaviour we must assume that a 

 soluble noxious material is produced by the vegetation of 

 the cocci. The disease was obtained by Koch by inocula- 

 tion of putrid material on the ear of mice ; at the same 

 time, however, bacilli which caused septicaemia were always 

 inoculated, and led to the death of the animal ; it was 

 not till field mice, which are immune against the 



14 



