62 Dr. Buchanan on the State of the Blood after taking Food. 



hungry so soon as the men fed with gelatin, as if the latter substance were dissolved 

 in the stomach more rapidly than arrow-root. 



The serum treated with yeast evolved carbonic acid gas in abundance, as did 

 also the crassamentum liquified by expression through a linen cloth. 



It thus appears that puro Starch, taken as food, gives no white 

 colour to the serum of the blood. This conclusion may be considered 

 as established, as it will bo seen below that the experiment was re- 

 peated three times, and always with tho same result. 



I now proceeded to test the hypothesis farther in reference to 

 azotized food. 



Eggs and Milk. — On the 30th April, 1844, D., after fasting eighteen hours, had 

 at noon a pudding, consisting of six eggs and a pint and a half of milk. He was 

 bled twice, to the extent of eight ounces. The blood first drawn, three hours after 

 the meal, gave but a small quantity of serum, which was opaline, resembling whey. 

 The serum of the blood last drawn, at seven hours after the meal, was much more 

 abundant. It had less whiteness, but still was not clear, being brownish bike syrup, 

 an appearance I have since found to depend frequently on the presence of a very 

 minute quantity of the red part of the blood. The crassamentum of the blood 

 first drawn had the translucent fibrinous crust well marked : that of the blood last 

 drawn was natural. 



Both specimens of serum showed, under the microscope, a few spherical granules. 

 On adding salt to that marked D. 3 hours, a white matter immediately rose to the 

 surface, and continued there some days without showing any tendency to fall to 

 the bottom. The other specimen marked D. 7 hours, gave, on the addition of salt, 

 much more of the white matter than its colour led me to expect, and, as in the 

 former case, the white matter showed no tendency to precipitate. In this respect, 

 as well as in general appearance, the white matter resembled closely a very abun- 

 dant specimen which I accidentally procured more than four years ago, and which 

 has continued at the top ever since, although the phial has been frequently uncorked. 

 I do not know from what diet it proceeded, but the present and two other trials 

 mentioned below seem to me to render probable that it may have been from eggs. 



I was particularly struck with the difference in the quantity of serum 

 procured by these two bleedings, practised upon the same person, with 

 an interval of only three hours ; that from the latter being about quad- 

 ruple that from the former. I at first supposed that a large quantity 

 of liquid must have been taken in the interval, but on inquiry I found 

 the man had taken no drink of any kind. The small quantity of tho 

 serum in the first case, therefore, was probably entirely owing to the 

 cup in which the blood was received being very full, and the surface 

 covered with air-bells. These air-bells cause the coagulum to adhere 

 to the rim and sides of the cup, and thus prevent the separation of 

 the serum. I have since more than once observed a similar deficiency 

 from tho same purely mechanical cause. 



Fibrin. — On the same day, E., after fasting the same length of time as D., had 

 a pound and a half of beaf steak, carefully freed from fat. He was bled at the 

 same periods after the meal. The relative quantities of serum from the two bleed- 

 ings were here reversed ; that from the latter bleeding being considerably less in 

 quantity, and apparently from the same cause. The serum at three hours was of 

 the colour of whey ; that at seven hours had the same hue, but less intense : in the 



