8 



Mr. C. H. KeUaway. The Effect of Certain 



in the crop at the time of feeding, one or two feeds were omitted till the crop 

 was empty. 



When other substances were added to the dietary, they were introduced 

 into the crop by means of a graduated syringe with a catheter tube attached. 

 " Marmite " was given in two strengths, 1 grm. in 2 c.c. or 2 grm. in 3 c.c, 

 made up with tap water. Olive oil and cod liver oil were administered in the 

 same way. Fat-free casein was given in the form of pellets, rolled from a 

 thick paste of the protein with water, and dried. 



In the first two weeks of feeding the birds retained the rice which was 

 placed in their crops, but later some of them tended to reject a portion, 

 though not all, of the feed. This tendency was only noticed in pigeons fed on 

 polished rice without the addition of " marmite." When " marmite " was 

 given, the rice was never rejected. 



The initial and final weights and the cloacal temperature were recorded. 

 The weighings were made with the crop empty. The final weighings were 

 made after death, and when necessary, the crop was opened and emptied. 



The birds were killed by a uniform method, the neck being rapidly 

 dislocated. In tlie earUer experiments a culture was taken from the heart's 

 blood in every case, but as these cultures were invariably sterile, this 

 precaution was discarded in tlie later experiments. After death the adrenals 

 were quickly dissected out, carefully cleaned from surrounding tissue and 

 dried with filter paper before weighing. A saline extract of the glands was 

 made, which was acidified, boiled, filtered, and made up to a known volume 

 of 3 c.c. to 5 c.c. This solution was always perfectly clear and suitable either 

 for colorimetric or physiological estimation of adrenaline. 



For the estimation of adrenaline the routine ifiethod used was that of 

 Folin, Cannon and Dennis (1912). It was found convenient in making up 

 the standard uric acid solution to use twice as much 4 per cent, lithium 

 carbonate solution as that recommended by. these authors (vide Seidell, 1913). 



Folin, Cannon and Dennis compared the results obtained by their method 

 with those given by the physiological estimation devised by Elliott (1912) in 

 a good many different animals, but it was thought advisable, in view of the 

 important part played by uric acid in avian metabolism, to institute a further 

 comparison on the suprarenal glands of normal and experimental birds. The 

 results of such comparison showed clearly that for purposes of this investiga- 

 tion the figures obtained by the colorimetric method indicated the actual 

 content of adrenaline, and that no appreciable error was introduced by the 

 presence of other substances which might be capable of giving the colorimetric 

 reaction. Table I gives some of the results, and I have introduced a typical 

 tracing of an estimation on a pithed spinal cat (fig. 1). 



