241 



turns on its side, the tail lying across the glass stage as 

 shown in the dotted outline. The silk cord h is used exactly 



Outline Sketch of Tadpole Trougb, actual size. 



as in the former case, to hold the animal in its place. A 

 cover glass is now laid on the tail. The tadpole should not 

 be left in more than three hours at a time. 



In the case of both fish and tadpole the circulation is apt to 

 flag during the first five or ten minutes, then revives. 



o. Young Water-Newt. — The circulation in the gills of the 

 young newt is well known as a beatitiful object ; the great 

 difficulty met with is that of keeping the animal still in the 

 zoophyte trough. I have found hydrate of cliloral answer 

 well here. The newt is put into a solution of eight grains to 

 the ounce, and left in until it becomes narcotised, which gene- 

 rally occurs in ten or fifteen minutes. Being now removed 

 to fresh water, the sleep continues for some hours. The cir- 

 culation continues active, and may now be examined with 

 great ease. 



The circulation in the frog's lung, and that last described, 

 though beautiful objects, are of no great value for physio- 

 logical purposes. The other examples are all suited for 

 practical Avork, 



I have employed all the methods described very frequently, 

 and can speak with confidence as to their efficiency. The 

 troughs are easily made from sheet gutta-percha, and are 

 managed without difficulty after a little practice. 



VOL. X. NEW SER. R 



