As has been shown by investigations and stated in a previous paper,1 infection with the flagellate Giardia lamblia often causes complaints and symptoms. The three characteristic signs are: (1) abdominal complaints, (2) anemia and (3) retarded development.
The abdominal complaints may easily be explained by the mechanical action of the parasites. When the disease is severe the intestines are inundated by innumerable protozoa, several of them being attached to each epithelial cell by aid of their peristomes. (In rabbits Jassinowski2 found a million organisms per square centimeter.) The flagellae protrude into the intestinal lumen and by their constant movement maintain a permanent inflammation.
The cause of the anemia has been studied for a long time. The supposition of Infurna3 that the protozoon "eats red blood corpuscles" is not plausible, especially in view of the fact that no blood corpuscles or their fragments or any products of their