372 Contributions to Physiological Technique 



handle, and corresponding ones on the tubes A and B near the barrel, 

 so that the spot on the end of the key handle pointing downwards in the 

 direction of C is of the colour of the spot on the tube A, or, as the case 

 may be, B, at the time in connection with it. Confusion as to fehe effect of 

 movements of the key on the perfusion is thus avoided. 



The form of stopcock described was shown at the meeting of the 

 Physiological Society on 20th January 1906. It is made by 

 Greiner and Friedrichs, and is supplied by Messrs Baird & 

 Tatlock, London. This also now applies to my earlier form of 

 perfusion-stopcock (loc. cit.), which is still of special use for 

 certain purposes. 



The apparatus and methods described in this paper have b^en mainly 

 worked out inDr Halliburton's laboratory, King's College, London. I 

 have, however, to acknowledge my indebtedness to Dr Brodie and Dr 

 Waller for the facilities put at my disposal in their laboratories also. 

 Grants in aid of the expenses incurred have been received from the 

 Glovernment Grant Committee of the Royal Society. 



