PRESIDENTIAL ADDRESS SECTION D. 71 



Thus, in the words of the English authors (pubHshed in 

 1916) : " No insect flagellate can be considered to be quite innocu- 

 ous to vertebrates until it has been put to the test." By these 

 experiments it was shown that the induced herpetomoniasis could 

 run an acute or a chronic course. In the acute cases, the flagel- 

 late form of the parasite was the more obvious one found at 

 death; in the chronic cases, the non-flagellate forms of the para- 

 site were more numerous. 



Under suitable conditions it is clear that insect flagellates can 

 be introduced into vertebrate hosts and can produce infections 

 therein. In some cases, as in the cold-blooded hosts, little 

 obvious ill-effect results; in others, as in mammals and in birds, 

 disease is manifested and often ends in death. 



The flagellates introduced into vertebrates retain their 

 powers of development on the same lines as when they are present 

 in the insect. The various species of Leishmania are probably 

 insect flagellates relatively long introduced into man and usually 

 perpetuating the non-flagellate form, though capable of assuming 

 the flagellate, herpetomonad facies in the internal organs of the 

 vertebrate or in the invertebrate host. 



Again, it is necessary to consider not part, but the whole, of 

 the life-history of an organism, and also the relation of the 

 parasite to the group to which it belongs. There is a line of 

 evolution common to each group, and in the cases under consi- 

 deration, Herpetomonas, Leishmania, Crithidia and Trypanosoma 

 should be considered not as isolated units but as ixiembers of the 

 Trypanosomidae. 



In connection with the Leishmania problem, one of the con- 

 clusions of the English workers* (1916) still holds and may be 

 quoted: " In areas where leishmaniases are endemic an exami- 

 nation should be made of all insects and other invertebrates 

 likely to come into contact with men or dogs or domestic vermin 

 like rats and mice, in order to ascertain if these invertebrates 

 harbour herpetomonads. Preventive measures should be directed 

 against such invertebrates, especially Arthropods. Further, it 

 is likelj^ that members of all classes of vertebrates, and especially 

 those members that are insectivorous, may serve as reservoirs for 

 leishmaniases, or, as they should preferably be termed, herpeto- 

 moniases. The virus may exist in such reservoirs in a very 

 attenuated condition and so be difficult of detection. From these 

 sources the herpetomonads may reach man by the agency of 

 ecto-parasites or flies, especially such as are sanguivorous." 



Clou de Biskra. — In North Africa a form of Oriental sore 

 known as " clou de Biskra," due to Leishmania tropica, occurs. 

 In 1921 the insect transmitter was determined by Ed. and Et. 

 Sergent, Parrot, Daratien and Beguet to be the sandfly, Phleho- 

 tomiis papatasii. They reproduced the disease by crushing flies in 

 saline solution and by vaccinating volunteers on the arm with the 

 emulsion. A papule containing the non-flagellate or Leishman- 

 Donovan bodies was thus produced. These experiments were 



* Journal of Parasitology, ii, p. 164. 



