THE BLOOD. 73 



submitted to examination, when, extraordinary to say, it 

 was perceived that the circulation was still vigorously main- 

 tained in the majority of the vessels. Anxious to know 

 how long this circulation would be continued, but fully ex- 

 pecting to see it cease every moment, myself and a friend, 

 John Coppin, Esq., of Lincoln's Inn, watched it for upwards 

 of an hour, at the end of which time the blood still flowed 

 onwards in many of the vessels, with scarcely abated vigour, 

 though in others, often the larger ones, the motion had alto- 

 gether ceased. The mutilated portion of the tongue was 

 then placed in water, in which it remained during the whole 

 of the night ; the next morning it was again examined, when 

 it was found that a tolerably active circulation still existed 

 in several of the smaller vessels. After this observation 

 the further examination of the fragment was abandoned. 

 The almost immediate cessation of the circulation, which 

 occurred in some of the larger vessels, admits of explanation 

 in the following way: In some vessels the blood globules 

 were seen escaping from their open extremities ; this effusion 

 of the globules frequently continued for two or three mi- 

 nutes, until the entire contents of such vessels became poured 

 out, when of course the circulation within them ceased, the 

 circulating fluid being expended ; in other capillaries the 

 current was seen to stop long before their contents had been 

 exhausted, in which case it was usually to be remarked that 

 some of the blood corpuscles contained in the vessels had col- 

 lected around their orifices, thus producing an impediment 

 to the further maintenance of the current. 



The foregoing observation is one of much interest and 

 importance ; for it seems to prove that the capillary circula- 

 tion is in a great measure independent of vital influences, and 

 that its persistence is mainly due to physical agencies. 



With a few observations on the mucous follicles situated 

 on the upper surface of the tongue of the frog we shall con- 

 clude our relation of the capillary circulation, as witnessed in 

 that organ. These follicles are glands reduced to the simplest 

 possible amount of organisation ; they are of a regularly 

 spherical form, and transparent texture ; they are situated in 



G 2 



