. A text-book of comparative physiology [microform] : for students and practitioners of comparative (veterinary) medicine. Physiology, Comparative; Veterinary physiology; Physiologie comparée; Physiologie vétérinaire. Ifi.'. THE CIRCULATION OF THE BLOOD. EvKRT tiaaue, eyery cell, requiring constant nourishment, some means must necessarily have been provided for the con- veyance of the blood to all parts of the orgasasm. We now enter upon the consideration of the meohanisma by which this is accomplished and the method of their regulation. Let us consider possible mechanisms, and then inquire in
. A text-book of comparative physiology [microform] : for students and practitioners of comparative (veterinary) medicine. Physiology, Comparative; Veterinary physiology; Physiologie comparée; Physiologie vétérinaire. Ifi.'. THE CIRCULATION OF THE BLOOD. EvKRT tiaaue, eyery cell, requiring constant nourishment, some means must necessarily have been provided for the con- veyance of the blood to all parts of the orgasasm. We now enter upon the consideration of the meohanisma by which this is accomplished and the method of their regulation. Let us consider possible mechanisms, and then inquire into their defects and the extent to which they are found embodied in nature. That there must be a central pump of some kind is evident. Assume that it is one-chambered, and with an outflow-pipe which is continued to form an inflow-pipe. This might be pro- vided with valves at the openings, by which energy would be saved by the prevention of regurgitation. In such a system things must go from bad to worse, as the tissues, by constantly tising up the prepared material of the blood, and adding to it their waste products, would effect their own gradual starvation and poisoning. It might be conceived, however, that waste at all events was got rid of by the blood being conducted through some elimi- nating organs ; and assume that one such at least is set aside for respiratory work. If the blood in its course anywhere passed through such organs, the end would be attained in some degree; but if the division of labor were considerable, we should suppose that, gaseous interchange being so very impor- tant as we have been led to see from the study of the chapters on general biology, and on muscle, organs to accomplish this work might receive the blood in due course and return it to the central pump in a condition eminently fit from a respiratory point of view. Such, however, would necessarily be associated with a more complicated pump ; and, if this were so constructed as to pre- vent t
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