xiii, b, 5 Haughwout: Flagellated and Ciliated Protozoa 227 



has given voice to the belief of the early workers in Manila 

 that many of these so-called harmless parasites are disease 

 producers. He adds that several of the Manila men (he wrote 

 in 1906) recognized a diarrhoea caused by "monads." He says: 



Several types of these parasites, when present in large numbers, are 

 very intimately connected with chronic diarrhoea and they are surely much 

 more important than they are generally considered to be. [p. 561.] 



He views Lamblia intestinalis with particular suspicion and 

 goes on to say that "when encountered in great numbers, it is 

 always associated with chronic diarrhoea, which disappears with 

 the destruction of the parasites." 



With Lamblia the conditions to me seem to be more obvious, 

 for here we have a parasite that we know attaches itself to the 

 epithelium by its sucking disk. It seems reasonable to conclude 

 that this alone would give rise to considerable irritation, to say 

 nothing of the facility with which toxic excretory products of 

 the parasite could be absorbed by the epithelium with which it 

 is in such close relation. In the cases of the other flagellated 

 protozoa we have less information on that point. Musgrave's 

 belief is that Lamblia "bears a decided causative relation to 

 the diarrhoea." 



Speaking of the intestinal parasites in general, including the 

 helminths, Musgrave concludes that — 



Whatever pathological significance may be attached to these parasites in 

 general, some of them, particularly the actively motile ones, such as monads, 

 surely aggravate amoebic ulcers in which they may be present. 



Fantham, Stephens, and Theobald (14) say that "like Tricho- 

 monas, Lamblia can multiply under inflammatory conditions of 

 the alimentary tract." 



Fantham and Porter, (12) following a series of carefully con- 

 ducted experiments, reached the conclusion that Lamblia is patho- 

 genic to man and is capable of producing diarrhoea, which may 

 be persistent or recurrent. Furthermore they hold the view, 

 which to me is of great importance in considering the relations 

 of the intestinal flagellates to man, that the virulence of the 

 parasite varies and lambliasis occurs in tropical and nontropical 

 countries. Lamblia cysts, they say, will remain infective for 

 some time. 



Whatever the case, the flagellates certainly often persist in 

 the stools for long periods of time, and diarrhoea is the rule when 

 they are present in large numbers. Whether they cause the 

 diarrhoea or whether the increase in their number is brought 

 about by the diarrhoea is quite another question. The most 



