28 ORGANISED FLUIDS. 



red corpuscles, which has been indicated, is a character com- 

 mon to them in the blood of all persons, and at every age. 

 Another variation as to size exists, which is, that the cor- 

 puscles are larger in the embryonic and foetal than they are 

 in adult existence.* This observation is important, inasmuch 

 as it seems to prove that the blood does not pass directly 

 from the maternal system into the foetal circulation, but that 

 the corpuscles are formed independently in the foetus. In 

 states of disease, also, it has been remarked by Mr. Gulliver 

 that there is even a still greater want of uniformity in the 

 measurements presented by the red corpuscles. 



A careful examination of the elaborate tables of Mr. Gul- 

 liver on the measurements of the blood corpuscles, appended 

 to the translation of Gerber's Minute Anatomy, tends to 

 show that a general, though not a very close or uniform 

 relation, exists between the size of the blood corpuscles 

 amongst the mammalia, and that of the animal from which 

 they proceed. These tables furnish more evidence in favour 

 of this co-relation than they do in support of the assertion 

 that has been made, that the dimensions of the corpuscle 

 depend upon the nature of the food. It would appear, 

 however, nevertheless, that the corpuscles of omnivora are 

 usually larger than those of carnivora, and these, again, 

 larger than those of herbivora.-\ In a perfectly natural family 



for 1839. The measurements which I have made of the human blood 

 corpuscle do not accord with those which are generally regarded as 

 correct : thus I find the average diameter of the blood globule of man to 

 be, when examined in the serum of the blood, about the ~j- of an inch, 

 and in water in which the corpuscles are smaller, as a necessary con- 

 sequence of the change of form, the -g^Vo- The micrometer employed by 

 me is a glass one, precisely similar to that made use of by Mr. Gulliver, 

 being furnished to me by the same eminent optician, Mr. Ross, from whom 

 his own was obtained. 



* This is the opinion of Hewson, Prevost, and Gulliver, and I have 

 myself to some extent confirmed its accuracy. 



f The largest globules which have as yet been discovered, are those of 

 the elephant ; the next in size, those of the capybara and rhinoceros ; the 

 smallest, according to the observations of Mr. Gulliver, are those of the napu 

 musk-deer. The corpuscles of the blood of the goat were formerly con- 



