Circulation of the Blood. 151 



round numbers), one eight-hundredth of an inch in 

 length, while those of the frog are one eleven-hun- 

 dredth ; and both these are singularly large compared 

 to those of man ; these latter are but one three-thou- 

 sand two-hundredths of an inch in diameter. 



The little newt was much more tractable than the 

 tadpole when placed in the live-box. It would remain 

 perfectly still for several minutes at a time and showed 

 no signs of discomfort. It was so small, and in 

 appearance so fragile, that I never touched it with 

 my hands, but always caught and lifted it with an ex- 

 temporized paper spoon, and poured it on to the live- 

 box. On looking attentively one day at its under 

 side, before placing it for inspection in the micro- 

 scope, I could distinguish a delicate pink spot 

 apparently fading and reappearing a number of 

 times every minute. The circulation in the branchiae 

 was then a familiar object to me, and was similar to, 

 but more beautiful than, that of the young tadpole. I 

 was also familiar with the appearance of the circula- 

 tion in the little newt's broad tail but this pink spo' 

 was something new to me, and was doubtless th( 

 heart, centre and origin of the movement which I had 

 hitherto traced only in detached portions. My sup- 

 position proved correct ; and I hope some reader may 

 be led by these remarks to capture and examine a 

 little water-newt and proceed much further than my 

 limited knowledge permitted me to do, in recording 

 the details of the wonderful spectacle which it presents 

 to view. 



