MAMMALIAN ANATOMY 
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B. PHYSIOLOGICAL DEMONSTRATIONS. 
1. Peristalsis. —Use a recently chloroformed or etherized frog, 
Necturus, or mammal (preferably the latter) from a half hour to an 
hour after feeding. Expose the intestines by opening the abdom¬ 
inal cavity. Observe the waves of contraction which pass slowly 
along the intestine and note the changes of form which they 
involve, and their effect in producing an onward movement of the 
contents of the region which is under observation. Note that 
these movements may be induced by mechanical stimulation. 
2. Appearance of the Food in Different Regions of the Diges¬ 
tive Tract during the Process of Digestion. —The specimens 
(cats and rabbits) used for this demonstration should be killed 
about a half hour or an hour after feeding. Open various regions 
of the digestive tract and compare the condition of the food mate¬ 
rial found in different regions, also note the conspicuous differ¬ 
ences which result from the difference in normal diet in such 
animals as the cat (carnivorous) and the rabbit (herbivorous). 
Note particularly the slightly digested and thus still recog¬ 
nizable food substances in the stomach, the creamy chyle in the 
small intestine, and the gradual accumulation of faecal matter 
which is left after the absorption of the nutritive portions of the 
food and which becomes more abundant and offensive in odor as a 
result of bacterial decomposition as the posterior region of the 
intestine is reached. Note also the degree to which the faeces are 
moulded into characteristic shapes before expulsion. Note, 
incidentally, the distended lymphatic vessels (lacteals) of the 
mesentery and follow these to the receptaculum chyli and thoracic 
duct (especially well seen in a cat which has been fed with rich 
milk about half an hour previous to chloroforming). 
C. HISTOLOGY. 
♦ 
1. The Alimentary Canal. 
Macroscopic Study. —In preparation for the microscopic study 
► 
of the intestine, examine macroscopically a short length of intes¬ 
tine (cat) which has been thoroughly hardened in formalin or some 
other fixing agent. With a sharp-scalpel make a clean transverse 
section of this and examine the cut end. Tease or tear apart the 
various layers. Note (a) the visceral peritoneal layer which 
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