s William A. Hilton 469 



2. Very long cylindrical or thread-like forms such as are found in 

 ox, opposum, camel and others (Figs. 11-13). 



3. Short thick mound-like, or low columnar forms, such as are found 

 in the caecum of rabbit and the small intestine of horse, although this 

 last very nearly comes under the next heading (Fig. 40). 



4. Cylindrical villi, such as are found in cat, dog, raccoon, and some 

 Insectivora and in the ileum of man (Figs. 17-19). 



The following table (page 470) gives the results of observations on 

 the form, size and number of villi in some of the mammals which were 

 available for study. 



In Macacus cynomolgus one of the primates, Eawitz, 94, describes 

 small villi and larger " ramified '' forms. In the intestine of a number 

 of monkeys examined leaf-like villi were observed, and in specimens of 

 Gorilla, Chimpanzee and Orang more or less leaf-like villi were found. 



In the intestine of a child at term, the villi are thin, more or less 

 leaf-like or fold-like. Many of these have broad bases and might almost 

 be considered folds. Their height is from .2-.4 mm. by .2-.7 mm. at 

 the base. The villi of a single region varied about as much as the villi 

 of different regions differed from one another. Although the villi in 

 one part of the intestine are very similar to those of other parts in 

 height and general character, a slight difference can be noted, for the 

 region near the pyloinis has m.ore fold-like villi than the central part. 

 The central part has more long villi of a triangular shape than has 

 the upper part of the intestine, and near the end of the small intestine 

 there are more villi with their tops nearly as broad as their bases. 

 There are from 10-12 villi per square mm., and in the whole intestine, 

 about 1,000,000 (Figs. 25-28) and (Intestinal curve No. 12). 



In adult man, Stohr describes leaf-shaped villi in the duodenum and 

 cylindrical in the rest of the intestine. Sappey estimates the number 

 of villi in man to be from 6,000,000 to 10,000,000. Others estimate 

 4,000,000. The greater number of villi in the adult are in the upper 

 part of the intestine, 10-18 per square mm.; farther towards the caecum, 

 8-14 per square mm. Many authors have described club-shaped villi 

 in the intestine of man, but when thin sections are made of cylindrical 

 villi which were fixed in some such fiuid as picric acid, club-shaped 

 forms are found; so it seemf improbable that club-shaped villi in man 

 are typical. 



Intestinal Curves of Mammals and Bieds. 

 In the following diagrams (p. 471) the relative height of villi is indi- 

 cated by the distance of the continuous curved lines above the heavy 



