1869.] 



Red Blood- corpuscle of Oviparous Vertebrata, 



349 



Sometimes, when the drop of blood has been skilfully mounted, the 

 majority of cells will remain for a long while without any trace of nucleus; 

 but, again, in almost every specimen, the nucleus in some few of the cells, 

 particularly in those nearest the edges, begins to appear so rapidly that it 

 is hardly possible to run over the whole field without finding some cells 

 with an equivocal appearance. 



It would follow, of course, from these observations that, if the living 

 blood were examined in the vessels, the corpuscle would show no trace of 

 any distinction of parts ; and this is so. Indeed, in my earlier observations *, 

 before I had learnt to mount a drop of blood for observation in a satisfactory 

 manner, I examined, at some length, blood in the vessels of the most 

 transparent parts I could select ; and several observations on the web and 

 lung of the frog and elsewhere were satisfactory. But still, when the cells 

 were thus somewhat obscured by intervening membrane, one could not 

 generally feel sure that the observation was so clear and complete, but 

 that a faintly marked nucleus might escape detection. Y^hile, therefore, 

 the result of observations on blood- cells in the vessels fully accords with 

 the description I have given, I do not think that the demonstration of the 

 fact, that while living they have no nucleus, can be made so plain and un- 

 equivocal as when they are removed from the vessels. 



The question naturally arises, Why, then, does not a nucleus form in the 

 mammalian corpuscle ? But while it is accepted that the great majority of 

 these corpuscles exhibit no nuclei after death, excellent observers still 

 affirm their occasional existence ; and I am convinced that an indistinct, 

 imperfectly formed "nucleus" is often seen; and the shadowy sub- 

 stance seen in many of the smaller oviparous cells after they have been 

 mounted for some time is very like that seen under similar circumstances 

 in some of the corpuscles of Mammalia. Many, too, affirm that these cor- 

 puscles do not exhibit that distinction of wall and contents which is 

 generally described. It appears to me that this* difference of opinion de- 

 pends on the changes they are prone to undergo. How far the absence of 

 a distinctly defined "nucleus" after death depends on their smaller size I 

 am not prepared to say. 



Many questions of course follow. For example, how far is this separa- 

 tion of the substance of a homogeneous f corpuscle into nucleus, cell- 

 membrane, and contents to be compared to the coagulation of the blood ? 

 and how do the agents which are known to influence the one process 

 affect the other? A still further and more important question is, How are 

 these changes in the corpuscles, and in the blood around them, related 1 

 But in this paper I propose to go no further than the statement that the 



* Made many years ago. Other observers have been unable to detect a nucleus in 

 the living cells within the vessels. 



t By the word homogeneous I do not mean to affirm that the substance of the cor- 

 puscle is of equal consistence throughout. The central may be the softest part of it 1 

 But I regard the corpuscle, in its whole substance, as "having the same nature." 



