I'EVKLorMEXT cF THE FCETVS. 109 



wards modilied to constitute the organs comprised between the oeso- 

 phagus and rectum. 



The mouth begins by a depression or cul-dc-sac, whicli is limited by 

 the maxillary tubercles ; it increases as it dips towards the pharynx, 

 from which it is only separated at last by a thin membrane ; this is 

 eventually absorbed, and the moutli then communicates with the com- 

 mencement of the digestive canal. Towards the third montli the mouth 

 is confounded with the nasal fossa?, but after this the palatine bones 

 appear, and finally isolate the two cavities. 



The tniujue is at first only a small protuberance from the maxillary 

 tubercles, but is completed by the addition of a little growth from the 

 second branchial arch. Its epithelium and glands are derived from the 

 external layer of the blastoderm ; they are apparent at the third or 

 fourth month. 



The j)}ianjux a.ni cesojjluKj us lei\<;then and widen as the foetus grows ; 

 the latter at first communicates with the trachea, but it gradually 

 closes, and ends by separating entirely from that tube. 



The stomach is formed by the dilatation of the anterior part of the 

 middle intestine. This dilatation is fusiform, its larger axis being 

 longitudinal ; but it soon curves on itself, and then this axis becomes 

 transversal. 



In Ruminants the stomach is single when it first appears, though it is 

 not long before furrows are observed on its outer surface ; while inter- 

 nally the particular septa are seen as in adult life. In the fa'tus the 

 stomach is small, but its volume increases rapidly after birth, when the 

 animal commences to take solid food. During the sucking period in 

 Ruminants, there is a predominance of the fourth over the other gastric 

 compartments ; but as soon as the young animal begins to consume 

 fibrous aliment, the rumen increases rapidly, until it is by far the 

 largest cavity. 



The intestines are at first of uniform calibre, thougli in a short time 

 it is easy to distinguish the different sections of which they are 

 ultimately composed. In hoofed animals the ciccum appears very early ; 

 it is situated near the omphalo-meseraic duct, which is detached from 

 the extremity of an intestinal loop that is drawn towards the umbilical 

 ring ; while the latter is becoming obliterated, this loop ascends in the 

 abdominal cavity. The intestines are quite smooth on their inner 

 surface during the first two months, and towards the third month show 

 the villi and glands of Lieberkiihn ; the Brunnerian glands and the 

 follicles are only seen later. 



The rectum arises from the posterior intestine, and is developed like 

 the other portions. 



With regard to the anus, there is observed towards the caudal 

 extremity of the foetus a depression analogous to the buccal cul-de-sac. 

 This becomes deeper, and joins the rectum and genitourinary organs ; 

 later, it separates from the last, and then belongs exclusively to the 

 alimentary canal. 



The APrEND.KGKs OF THE .\LiMKNT.\uv cAN.\L are the salivary glands, 

 teeth, liver, pancreas, and spleen. The salivarri i/lands are developed 

 in a solid cellular tubercle, which is connected with the epithelium at the 

 upper part of the digestive apparatus. With the growth of this tubercle, 

 it is converted into a series of cavities having the form of glandular cj//s- 

 de-sac. The submaxillary gland appears first, and is entire in a foetus 

 of only twelve lines in length ; the parotid gland is the last formed. 



