OF THE BLOOD AND CIBCULATION. 



213 



the little molecules of the blood are seen in ceaseless motion 

 and alive, but altogether without inherent activity, now borne 

 forward as upon gentle waves, and then pushed more im- 

 petuously along ; now advancing in serried ranks, now 

 threading their way in single files, the entire phenomena de- 

 pendent upon the activity of the central organ. In the most 

 minute intermediate vessels of all, a great degree of repose is 



Fig 230. Portion of the lung of a live Triton drawn under the micro- 

 scope, and magnified 150 times; a, 6, c, streams of venous blood; <7, a 

 branch of the pulmonary artery. The very delicate capillaries sen-ing as 

 bonds of union between the pulmonary vessels, are seen playing round 

 little islets of the substance of the lung. The clear space between the 

 current of the blood and the walls of the vessels observed in the larger 

 branches is almost entirely wanting here. The lymph granules, therefore, 

 are observed mixed with the general torrent. The arrows indicate the 

 course of the currents. 



