238 FRANKLIN PARADISE JOHNSON 



Bujard ('09) made an extensive study of the villi in a number 

 of vertebrates and as he has given a resume of the Uterature 

 on this subject, another need not be presented here. With 

 regard to the vilh of mammals Bujard has reached the follow- 

 ing conclusions: In herbivorous mammals, where a large re- 

 siduum of food material is found in the intestine, the intestine 

 is long and the villi small and few. In insectivores, frugivores, 

 and omnivores, where there is only a moderate amount of food 

 material present, the length of the intestine is medium and the 

 villi large and numerous; while in the carnivores, where a mini- 

 mum residuum of food is left, the intestine is shorter and the 

 villi are narrow, long and pointed, and very numerous. How- 

 ever, Bujard makes no mention of the fact that it is the amount 

 of residuum which determines the amount of distention of the 

 intestine, and that it is this in turn which determines the shape 

 of the villi. He believes, rather, that it is the nature of the 

 food material itself which is the active factor in producing dif- 

 ferent shapes. To substantiate this view he has performed 

 experiments upon the intestines of white rats, in which he found 

 that after the continued feeding (140 to 380 days) of milk and 

 meat diets, the villi become long and narrow, while on vege- 

 tarian diets, the villi become broader and shorter. Unfortu- 

 nately, in his descriptions of villi, he does not state whether 

 the pieces of intestine he examined were in a contracted, par- 

 tially contracted, or in a distended condition. 



As will be seen from the following experiments, the variations 

 in the form of villi are so great under normal conditions of dis- 

 tention and contraction, that it is necessary, in order to obtain 

 a comparable series from a number of animals, to select i^ieces 

 of intestine contracted or distended to like extents, and it seems 

 desirable that all experiments of alimentation of the nature of 

 those performed by Bujard, should be preceded by a study of 

 the effects of contraction and distention upon the shapes of 

 the villi and glands. 



