Section 32. The processes that occur in the remaining portions of the alimentary canal are imperfectly understood. The caecum is so large in the rabbit that it must almost certainly be of considerable importance. In carnivorous animals it may be so much reduced as to be practically absent. An important factor in the diet of the herbivorous animals, and one absent from the food of the carnivora, is that carbohydrate, the building material of all green-meat- [food], cellulose, and there is some ground for thinking that the caecum is probably a region of special fermentive action upon it. The pancreatic juice, it may be noted, exercises a slight digestive activity upon this substance. Section 33. Water is most largely absorbed in the large intestine, and in it the rejected (mainly insoluble) portion of the food gradually acquires its dark colour and other faecal characteristics. 3. _The Circulation_ Section 34. The next thing to consider is the distribution of the food material absorbed through the walls of the alimentary canal to the living and active parts of the body. This is one of the functions of the series of structures-- heart and blood-vessels, called the circulation, circulatory system, or vascular system. It is not the only function. The blood also carries the oxygen from the lungs to the various parts where work is done and kataboly occurs, and it carries away the katastases to the points where they are excreted-- the carbon dioxide and some water to the lungs, water and urea to the kidneys, sulphur compounds of some kind to the liver. Section 35. The blood (Figure 4, Sheet 2) is not homogeneous; under the low power of the microscope it may be seen to consist of-- (1.) a clear fluid, the plasma, in which float-- (2.) a few transparent colourless bodies of indefinite and changing shape, and having a central brighter portion, the nucleus with a still brighter dot therein the nucleolus-- the white corpuscles (w.c.), and (3.) flat round discs, without a nucleus, the red corpuscles (r.c.), greatly more numerous than the white.