434 



OF FOOD, AND THE DIGESTIVE PROCESS. 



so, to that exerted by hydrochloric acid, it is by no means impossible that it 

 may be subservient to the completion of the digestive process in the case in 

 question ; since, the larger the proportion of the aliment composed of saccha- 

 rine matters, the greater will be the importance of a thorough extraction of its 

 albuminous constituents. 



456. The walls of the lower part of the Small Intestine are beset with ele- 

 vated patches, that are formed by the aggregation of the bodies known as the 

 "Peyerian glandulae;" bodies of a similar kind, however, also occur separately, 

 and are then known as the "glandulse solitariae." The " glands of Peyer," 

 when examined in a healthy mucous membrane, present the appearance of cir- 

 cular, white, slightly raised spots, about a line in diameter; over which the 

 membrane is usually less set with villi, and very often entirely free from them. 

 Each of these white spots, of which a large number are contained in the 

 agminated glands, is surrounded by a zone of openings like those of the follicles 

 of Lieberkiihn, which lead (as do those) into tubular caeca (Figs. 127, 128). 



Not unfrequently, however, 

 the centre of the spot exhibits 

 a very definite opening, which 

 may be compared to the pupil 

 of the eye; and this opening, 

 though formerly supposed to 

 be abnormal, appears from the 

 observations of Prof, Krause 1 

 and Allen Thomson 3 to be 

 the normal condition of the 

 body at a certain stage of its 

 development. In the Pig, on 

 which the greater number of 

 Dr. A. Thomson's observations 

 were made, some patches often 

 present no openings, whilst in 

 others almost all the cavities 

 are open and empty; and in 

 a third set, open and closed 

 vesicles are irregularly dis- 

 posed in the same patch (Fig. 

 open vesicles were observed 



A. Portion of a patch of Peyerian Qlandulce from the ileum of 

 the Pig, as seen from the deep surface, the serous, muscular, and 

 areolar coats having heen dissected off; the darker vesicles are 

 open and empty, the paler closed and full ; magnified 3 diame- 

 ters. B. Two of these vesicles, viewed from the inner surface of 

 the intestine, one of them closed and full, the other open and 

 empty, with villi and apertures of mucous follicles in their neigh- 

 borhood ; magnified 15 diameters. 



Fig. 130. 



129). The 



Vertical section of two of the Peyerian Glan- 

 dulce from the ileum of the Pig, one of them 

 closed and full, the other open and empty, with 

 their neighboring villi ; magnified 15 diameters : 

 a, cellular contents of the veskle; magnified 

 250 diameters. 



more frequently in the ileum than in the 

 upper part of the intestine; and it ap- 

 peared to be in those parts of the intes- 

 tine which contained the more fluid, dark- 

 colored, and bilious matter, that the open 

 vesicles were almost invariably found; 

 while in those parts of the gut which 

 contained a light-colored chymous or chy- 

 lous mass, which were more contracted, 

 and in which the coats appeared thickened 

 by the imbibition of chyle, the vesicles were 

 all closed and full of their usual contents. 

 These consist of minute granular cells, 

 mixed with molecules of various sizes (Fig. 

 130) ; and it has not seemed an unreason- 

 able supposition, that each of these bodies 



1 "Muller's Archiv.," 1837 and 1839. 



2 "Annals of Anatomy and Physiology," No. 1, p. 35. 



