DIGESTIVE SYSTEM 



arbitrary expressions ; but, if we assume that a relative length not 

 exceeding 5 indicates a short, and one of more than 8 a long gut, 

 we find that the Intestinal Canal is very short in all purely frugi- 

 vorous and insectivorous birds, while it is very long in those which 

 live upon fishes, carrion, grain, and grass. It must, however, be 

 remarked that, according to the nature of the food, a short intes- 

 tinal canal is often compensated by its Avidth either wholly or in 

 part, as of the rectum, or by the presence of large cseca. Conse- 

 quently all these points have to be considered in using the features 

 of the intestine for taxonomic purposes. Gxteris paribus, the rela- 

 tive length of the canal is as good a character as many others, and 

 occasionally by it alone closely -allied species can be determined. 

 The subjoined table shews the measurements of the intestine in a 

 few forms ; but for fuller information the reader may be referred 

 to (Bronn's) Kl & Ordn. Thier-E. Vogel, pp. 590-661 and 700, where 

 the respective measurements of Jiearly 400 birds will be found. 



dom 



Struthio camelus . 

 Casufirius indicus . 

 Splicniscus minor . 

 Anser cinereus, var. 

 Procellai'ia leaehi . 

 Ardea ciiierea . 

 Gallus bankiva, var. dom 

 Syrrhaptes paradoxus . 

 Columba livia, var. dom 

 Paudion haliaetus . . 

 Astnr palumbarius . . 

 Corythaix persa. 

 Cypselus apus . 

 Corvus corax 

 ivlanucodia atra . 

 Passer domestieus . 



Absolute Length 

 of' 

 1 Csecum. Rectum. 



■2 

 •5 



20 



cm. 



70 



13 

 2 



24 

 

 



17 



12 

 0-8 

 0-3 

 0-7 

 

 



l*-4 

 0-5 

 0-2 



Length of 



Intestinal Canal. 



Absolute : Relative 



cm. 

 820 

 28 



7 

 18 



1-5 

 10 



8-11 

 10 



4 



9 



7 



cm. 



1430 



ISO 



223 



260 



29 



212 



136-170 



SO 



108-132 



300 



108 



42 



17 



120 



29 



21 



20 



3-4 

 16 

 12 



5 

 10 



8-10 



9 

 Il- 

 ls 



6 



13 



2-3 



5-6 



In early embryonic stages the Intestinal Canal is a straight 

 tube ; but, as its growth proceeds far more rapidly than that of the 

 body-cavity, it is necessarily thrown into folds or loops. Moreover, 

 since it is suspended from the vertebral column by the mesentery, or 

 lining of the body-cavity, its several folds are thereby connected 

 with one another in various ways, and their number and shape 

 depend to a great extent upon the space available in the cavity, as 

 well as upon the shape, size, and position of the stomach and 

 neighbouring organs ; but the various ways in which the small in- 

 testine is stowed away in different birds exhibit types so definite 

 and constant that they cannot be considered accidental or meaning- 

 less features. On the contrary, a somewhat exhaustive study of its 



