MICROBES AND TOXINS 



plasmodium of malaria present the best example of the labour 

 necessary to reconstruct the biology of a parasite common to 

 man and the mosquito. 



PROTOZOAL DISEASES 

 Rhizopods 



Amoebae. Amoebic dysentery and liver abscess. A ciliated infusorian, 

 Balantidium coli, may produce the same disorders. 



Haematozoa 1 



Trypanosomes. Sleeping sickness (human Trypanosomiasis). Trypano- 



somiasis of animals : nagana, surra, dourine, mal-de-Caderas. 

 Leishmania. " Leishmanioses " : Kala-azar (the oriental sore, Biskra 



button, Aleppo button, etc., being particular cases). 

 Piroplasmoses. Bovine Piroplasmoses (due to Piroplasma bigeminum, 



P. parvum, P. mutans ; canine, ovine, and equine Piroplasmoses. 

 Plasmodia. Malaria with its varieties: tertian, quartan, and sestivo- 



autumnal or tropical tertian. 



Spirochsetes. Relapsing fever (European, African, Asiatic, American). 

 The spirillosis of fowls and geese. 

 Human spirillosis = syphilis. 



The more the study of these cycles was advanced, the more 

 one was compelled to acknowledge relationships between forms 



which did not seem in 

 the least related. Es- 

 tablished classifications 

 have several times got 

 into difficulties from 

 trying to express genea- 

 logical relationships 

 between very diverse 

 forms. Schaudinn saw in 

 the life-cycle of the same 

 parasite trypanosomes, 

 spirochaetes, and 

 amoeboid forms. It has 

 been necessary to re- 

 cognise a relationship between the sporozoa (haemo-sporidia) 

 and the flagellates. The affinities of the spirilla and spiro- 



1 According to the recent views of Hartmann, originating in Schaudinn's 

 ideas, all the haematozoa mentioned here may properly be arranged in one 

 natural group. 



FIG. 55. Trypanosomes of sleeping sick- 

 ness ( Trypanosoma gambiense) : the 

 form on the extreme right is in process 

 of division. 



