1909.] 



On Trypanosoma eberthi (Kent), etc. 



387 



Well to consider shortly the varying conditions which these parasites have' 

 to withstand in the course of digestion. Unfortunately, very little seems to 

 be known as to the part played by the caeca in the metabolism of the bird, 

 and apparently much the same statement may be made as regards the 

 conversion of the fluid intestinal contents into the more solid faeces in any 

 animal. The body temperature of birds is given by Tigerstedt as lying 

 between 39 0- 4 to 43°*9 C. The temperature of one of our fowls measured in 

 the axilla was 39 a 5 C, which is possibly rather low. 



The condition of the csecal content can vary very greatly ; in what we* 

 have termed the normal csecal condition the caeca are full of a light brownish 

 fluid containing a large number of small gas bubbles. (In one Irish hen 

 there was an enormous development of gas, and a strong smell of 

 sulphuretted hydrogen ; the presence of the sulphuretted hydrogen was 

 possibly correlated with the presence of a rounded plump bacterium found 

 in very large numbers in this hen.) 



The most characteristic feature of the bacterial flora in this stage of 

 digestion is a very active vibrio which has been met quite high up the 

 intestine. When the caeca are in this condition, the rectum is frequently : 

 empty, and if it is full the contents, though hard, are largely made up of 

 fibres and husks of corn. In what we term the rectal condition of the caeca, 

 the caeca are filled with a dark firm mass ; the rectum then may be filled with 

 the same substance, or u may be empty, in which case the animal has . 

 probably recently defecated. In the transitional stages between the 

 normal and rectal conditions the bacterial flora undergoes a marked 

 change, the vibrio becomes much rarer, and large numbers of cocci and long 

 slender bacteria are met with. It is evident that in the course of this 

 change of the nature of the caecal contents, very complicated physical and 

 chemical factors may be at work, not only owing to the action of the 

 walls of the alimentary canal itself but also to that of the bacteria. To 

 single out only one of these factors, the question of the changes in the 

 osmotic pressure of the surrounding medium of the parasite becomes a very 

 important one. 



It is a general practice for workers on the intestinal protozoa to carry out 

 extended observations in a solution of sodium chloride, isotonic witli the 

 blood, and as regards the fowl, Hamburger, in his recent work on 

 ' Osmotischer Druck und Ionenlehre,' gives two determinations : on p. 176 

 the figures - 45 to 0417 per cent, of sodium chloride are mentioned as the 

 result of plasmolytic methods on blood corpuscles. On p. 458 he gives 0591 

 to - 605 per cent, sodium chloride as a figure arrived at by the freezing-point 

 method. We used a tap water solution of - 7 per cent. NaCl, but we think 

 vol. lxxxi. — B. 2 F 



