The direct influence of gradual variations of temperature upon the rate of beat of the dog's heart / by H. Newell Martin.

  • Martin, H. Newell (Henry Newell), 1848-1896.
Date:
1883
Catalogue details

Licence: Public Domain Mark

Credit: The direct influence of gradual variations of temperature upon the rate of beat of the dog's heart / by H. Newell Martin. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

    20/42 (page 676)
    this quantity it was possible to obtain from Dogs. When four htres or more of blood are wanted it becomes practically impossible to use Dog's blood, and so some other had to be selected. After several trials Calf's blood was chosen. This blood, how- ever, nourishes the heart less satisfactorily, and hence the earlier indications of commencing death. With respect to the choice of blood I add a few words which may be of aid to any one desirous to repeat my experiments. It is important to have it from quite young Calves ; that is to say, from animals which are still suckling : a point of itself of some interest when considered in connexion with the well known fact that the chemical composition of the urine of the nurslings of Herbivora shows that their nutritional processes agree in the main with those of adult Carnivora, and differ essentially from those of the adults of their own species. In spite of all care I used to be frequently disappointed by the death of the isolated heart before any satisfactory number of observations could be carried out upon it, even in cases when I could think of no cause for the failure. Light broke upon me when the laboratory attendant, whose duty it was to bring the blood from the slaughter-house, remarked one day that it seemed to him that we nearly always got on better when he did not get the blood from wharf calves. On questioning, I found that wharf calves was the term employed by Baltimore butchers to indicate animals which, though still young enough to yield veal, were of such age that they had long ceased to live on milk. Since the blood of such Calves has been rejected the percentage of failures has considerably decreased. It is hardly necessary to add that care must be taken that no extraneous matter enters the blood during its collection. Baltimore butchers stun the Calves and then cut their throats, and while the blood flows out vomiting frequently occurs and sends the contents of the stomach into the collecting pail. The blood from each animal has therefore to be collected separately, so that the quantity already obtained may not be rendered unfit for use by admixture with matters from the stomach of another animal. Even with the best obtainable Calf's blood, however, the results are not as satis- factory as with Dog's blood. Not only does the heart die sooner, but other changes occur which shorten the time during which an experiment can be carried on. The most marked of these is lung oedema, which nearly always takes place in the course of an hour and a half, to such an extent as to seriously impede the pulmonary circulation and the aeration of the blood in the lungs. In consequence, the supply of blood to the left heart is hindered, and the right heart becomes gorged, and its auricle finally paralyzed; and this, of course, puts an end to an experiment. Another trouble which is apt to occur when Calf's blood is used is considerable pericardial exudation, often to such an extent as to seriously interfere with the beat of the heart. This difilculty may, however, be readily avoided by cutting a small hole in the pericardium as soon as the heart is placed in the warm chamber. A third difficulty met with when Calf's blood is employed is more serious. Many observers have noted on the isolated Frog's