xiii, b, 5 Haughwout: Flagellated and Ciliated Protozoa 245 



sibility that the invading flagellates will give rise to symptoms of one kind 

 or another. * * * If such invasion can occur [speaking of Tricho- 

 monas], probably through a surface broken by some other infection, or 

 irritant such as sand, it is possible that the flagellates might aggravate the 

 lesion or produce definite: symptoms. 



So much for Lamblia infections in the lower animals; but 

 Fantham and Porter (12) carry the matter farther in their 

 inquiry into human lambliasis. They say: 



We may say at once that in both human and animal lambliasis stools, 

 as well as at post-mortem examinations, erosion and distortion of the 

 intestinal epithelial cells occurred, owing to the direct suctorial action of 

 the flagellate Lamblia. 10 



Woodcock (52) holds in the case of flagellate infections in man 

 that if the normal bowel condition becomes disturbed and its 

 resistance lowered the balance between the host and the parasite 

 is no longer maintained, and the parasites will, therefore, mul- 

 tiply more rapidly and in turn bring about a more intense re- 

 action on the part of the host, establishing a vicious circle. He 

 believes that the presence of a vast number of parasites in the 

 intestine "with the concomitant production of waste metabolic 

 substances, is sufficient to irritate the mucosa and give rise to 

 deleterious and toxic effects." He adds : 



Fortunately, the flagellates appear to be unable to penetrate the mucosa 

 in the way that E. histolytica and Balayitidium can (given favourable con- 

 ditions), and therefore, never (?) produce true dysenteric symptoms, the 

 derangement being generally limited to severe or mild diarrhoea. 



Minchin(34) raises the old question as to whether the migra- 

 tion of the parasite, when the tissues are involved, is the cause 

 of the diseased state or if the diseased state of the host gives 

 the parasite a chance to spread to other parts of the body. Aside 

 from that point, he makes the exceedingly pertinent remark that 

 the fact that intestinal parasites can pass from the gut to the 

 blood is of phylogenetic as well as of practical importance. 



Walker (49) discusses the case of Balantidium coli infections 

 in man. He speaks of the absence of liver involvement by this 

 parasite, quoting the old case of Stockvis,(48) in which "Para- 

 maecium" {Balantidium ?) was recovered from the sputum, the 

 parasites presumably having come from the liver by way of 

 the lung. 



In connection with the involvement of the liver in entamoe- 

 biasis and balantidiosis it is customary to regard the route of 

 invasion as lying through the portal circulation, the parasites 

 entering the radicles of the portal vein. It must be borne in 



111 The italics are mine.— -F. G. H. 



