THE BLOOD-CURRENTS. 245 



expanding immediately as the action passes on) and 

 the globules are forcibly expelled through the narrow 

 but open extremity. Meanwliile, globules from around 

 the other end have rushed in, as soon as that part 

 resumed its usual width, which in turn are driven 

 forward by a periodic repetition of the systole and 

 diastole. 



The globules thus periodically driven forth from 

 the heart now let us watch, and see what becomes of 

 them. They do not appear to pass into any defined 

 system of vessels that we may call arteries, but to find 

 their way through the interstices of the various organs 

 in the general cavity of the body. 



The greater number of globules pass immediately 

 from the heart through a vessel into the short foot- 

 stalk, where they accumulate in a large reservoir. 

 But the rest pass up along the side of the body, 

 which (in the aspect in which we are looking at it, 

 and as it is represented in the figure) is the right. As 

 they proceed, (by jerks of course, impelled by the 

 contractions of the heart) some find their way into 

 the space between the breathing surfaces, but how I 

 can hardly say, if the breathing organ is indeed, as I 

 had supposed, a sac ; — they certainly do slip in be- 

 tween the rows of oval rings, and wind along down 

 between the rings in irregular courses. Of course, I 

 know that I am liable to mistake here, confounding, 

 through the transparency of the organs, those globules 

 which are outside the breathing sac with those that 

 are within it ; still after the utmost care by focusing, 

 I think I am sure the globules do pass as I have said ; 

 besides those which wind along on the outside, or 



I 



