156 



MICROBES AND TOXINS 



Fig. 62. — Mallory bodies; the hypothetical 

 microbe of scarlatina under different 

 aspects. (After Calkins. ) 



Borrel has discovered in the cells of molluscum contagiosum 

 minute corpuscles very equal in size and distinct from the 

 nucleus, from the chromatin and from the protoplasm : they 

 are small enough to pass through filters, and sufficiently 

 abundant and resistant to physical influences, as temperature 



and drying, to explain 

 the powerful nature of 

 the contagium in these 

 diseases. 



This may perhaps be 

 the type of microbe so 

 long sought for in 

 small-pox and granular 

 conjunctivitis, but it is 

 necessary to speak with 

 reserve as cultivation 

 has not yet been suc- 

 cessful. What is certain is that there exist ultra-microscopic 

 bacteria and protozoa sufficiently small to traverse the pores of 

 filters made of asbestos, porcelain, plaster, or infusorian earth. 

 Great discoveries are still to be made in this domain — a domain 

 opened up twelve years ago by the study of foot-and-mouth 

 disease and pleuro-pneumonia. 



The curiosity of investigators ought not to be monopolised 

 by the diseases occurring in man and animals. There is no 

 reason why there should not be invisible microbes elsewhere 

 in those fermentations which go on everywhere in nature. 

 They may also quite well play a part in the life-cycle of plants. 

 Just as insects produce injuries and mutilations in plants, so 

 the ultra-microscopic microbes may be responsible for the 

 variations and mutatioiis which occur in the vegetable world. 

 Microbiology may hope here again to bring its support to the 

 Darwinian doctrine. 



