704 ORDEE: DIPLOMONADIDA 



diarrhoeic in form, blood never occurs in pure Giardia infections. Westphal 

 and Georgi (1923) have noted that in certain chronic disorders associated 

 with jaundice the flagellates were present in large numbers in the duo- 

 denum, and in one case their presence in the gall bladder was demon- 

 strated at operation. They believe that a definite inflammatory condition 

 of the bile duct and gall bladder is set up by their presence. 



Animal Experiments. — The fact that rats and mice are often infected 

 with Giardia led Grassi (1879-1888) to express the opinion that human 

 beings become infected from these animals. He claimed to have infected 

 himself by means of the intestinal contents of rats, Perroncito (1901) 

 stated that he had infected mice by feeding them with material from 

 human cases, and Fantham and Porter (1916) made similar claims. The 

 fact that mice are often naturally infected with Giardia renders such 

 experiments very doubtful. Even prolonged examination of the faeces 

 of the animals before the experiment may fail to exclude the natural 

 infection. More recently, Deschiens (1921) has studied the question more 

 fully. He was convinced that he had succeeded in infecting animals by 

 means of human material. Thus, two cats were infected from human 

 beings and two others from mice. All four animals developed a dysen- 

 teric condition which w^as fatal in three of the cases. Five mice naturally 

 infected with Giardia failed to react to the human form, whereas five 

 mice which were not naturally infected developed an infection with 

 dysenteric symptoms, which proved fatal in three. The flagellates which 

 appeared in the cats after ingestion of human material were said to be 

 identical with those occurring after infection from mice. From these 

 results Deschiens was inclined to regard G. intestinalis of man and G. muris 

 of rats and mice as identical. Furthermore, he is convinced of the 

 pathogenic role of these flagellates. It should be remembered, however, 

 that both cats and mice are often found naturally infected. 



Simon (1922) obtained white rats and wild rats which were free from 

 Giardia infections. Attempts to infect them with G. intestinalis of man 

 failed entirely, though they were readily infected with Giardia of mice. 

 For this reason, and on morphological grounds, he concludes that the 

 human infection is not contracted from rodents, but passes directly from 

 man to man. The writer has attempted on several occasions to infect 

 mice with the cysts of the human form, but has never succeeded. Quite 

 recently he has conducted a carefully controlled experiment with four 

 kittens. One of them had a natural Giardia infection. About 10 to 20 c.c. 

 of fluid human stool containing numerous cysts was administered to each 

 animal by means of an oesophageal tube. All four developed diarrhoea, 

 and two actually passed blood and mucus. Cysts of Giardia were present 

 in the faeces for two days, after which they disappeared, except in the case 



