Vegetable Albumen, Fat and Starch. 323 



minds that the presence of traces of an albuminous substance 

 in the white matter of this serum was established ; and we had 

 subsequently opportunities of obtaining this matter in larger 

 quantities, so as to confirm the previous experiments. 



These results led to a series of researches upon the effect 

 of food on animals, and also on man ; from which it was clearly 

 demonstrated that the white colour of the serum in healthy ani- 

 mals is dependent on the introduction of food into the system. 

 The detail of one or two experiments will place this conclusion 

 in a distinct point of view. It was necessary for this purpose 

 to observe the characters of the serum of an individual who 

 had not tasted food for such a space of time that the effects of 

 the previous meal should have disappeared. On the 10th of 

 March 1844, from a stout young man, aged thirty, who had 

 tasted no food from the preceding evening at six o'clock p.m., 

 two ounces of blood were taken at noon, or at an interval of eigh- 

 teen hours after a meal. The blood coagulated on standing 

 in the usual manner, and the supernatant serum was found to 

 possess a pale yellow colour, and to be perfectly clear and 

 limpid. 



After the abstraction of the blood, the individual dined 

 upon twenty-four ounces of a pudding consisting of two parts 

 of wheat flour and one part of suet, seasoned with salt. At 

 three o'clock, or in about three hours after the food had been 

 swallowed, seven ounces of blood were taken by venesection 

 from the arm. The clot formed as usual, no appearance of 

 a buffy coat presenting itself. The serum was whitish and 

 opake ; when heated it became more translucent, apparentl}' 

 from the solution of some of the solid particles diff*used through 

 it, or, as was afterwards apparent, from the liquefaction of the 

 fatty matter diff'used through the serum. The whole fluid 

 possessed a somewhat syrupy cast of appearance, and was very 

 heavy, its specific gravity being as high as 1029*8. Compa- 

 ring this density with the average density of serum as we find 

 it in physiological works, 1026| by Dr. Thomson, 1027 to 

 1029 by M'liller, it must be pronounced high; but as the spe- 

 cific gravity of this fluid has never been properly estimated in 

 perhaps the truly healthy condition of animals, and more 

 especially in parallel cases with that described, no conclusion 

 can be deduced in reference to the density of the serum as 

 compared with the normal standard. On throwing the serum . 

 upon a filter, a portion of while matter remained attached to 

 its interior surface, while the liquid which passed through re- 

 tained still a milky aspect; but perhaps the most interesting 

 result obtained by this experiment was, that on drying the 

 filter and holding it between the eye and the light, it was 



Z2 



