280 MOVEMENT 



Some defibrinatecl bullock's blood was poured into 

 the funnel so as to fill it three parts full. After a few 

 minutes, the blood was seen to fill the auricle, and then 

 almost immediately to be discharged into the ventricle ; 

 the latter, in its turn, contracted and sent its contents 

 through the tube, from which it was emptied into 

 the funnel through the attached pipe. 



Instead of the weak and occasional movements 

 executed by the heart when depleted of blood, an 

 energetic circulation was established, and continued 

 from six to ten hours, and sometimes even longer, the 

 time being dependent on the season of the year. 

 Under the influence of the heart's activity, the blood 

 soon assumed a veinous character, and therefore it was 

 found essential to renew it from time to time, in 

 order that the energy of the artificial circulation 

 might be maintained. 



The photographs thus obtained can only be repre- 

 sented as shadows, because the red colouration of the 

 tortoise's heart is not photogenic, and cannot, therefore, 

 form an image by reflection, and give the configuration 

 which is necessary for understanding the changes in 

 form of the auricles and ventricles, which occur from 

 moment to moment. 



These silhouettes, however, enable one to follow the 

 various stages by which the blood circulates through 

 the heart, and the tubes which communicate with the 

 cavities of that organ. As the photograph represented 

 in Fig. 197 has to contain several images, we re- 

 duced as far as possible the component parts of the 

 apparatus for carrying on the artificial circulation. 

 The broad funnel in Fig. 196 has been replaced by 

 a thick glass tube pointed at the end, so as to pass 

 through the vein and gain entrance to the auricle. 

 This constitutes the veinous reservoir. Another and 

 finer tube, representing the artery, fits into the orifice 



