THE 
VETERINARIAN. 
VOL. XXVII, 
No. 31 G. 
APRIL, 1854. 
Third Series, 
No. 76. 
SOME THOUGHTS CONCERNING THE ACCEPTED 
PHYSIOLOGY OF THE HEART. 
By Edward Mayhew, M.R.C.V.S., London. 
Nothing new, one would at first glance conclude, could 
be said- regarding so hackneyed a subject. After the number 
of eminent men who have minutely considered the circulation 
and every portion of its apparatus, he, the generality of 
readers will be inclined to say, must be a bold man who pre- 
sumes to utter another word about the matter. However, 
leaving all ideas concerning presumption to those who delight 
in them, anatomy has laid bare certain facts, concerning 
which reflection has induced me to come to certain con- 
clusions. 
In the first place, it is very general to say, arteries have 
three coats, one of which is muscular ; also that veins have 
three coats, neither of which is muscular. Regarding the 
muscular coat of arteries, it has long been given up that they 
have any covering like red muscular fibre. Yet those who 
are anxious to establish their muscular character, and have 
not been pleased with an investment of simple elastic tissue, 
now assert they have a coating of yellow substance mingled 
with much organic fibre. 
I know not whether this assertion be correct or not. I 
have in vain endeavoured to discover anything approaching 
to organic fibre in the tubes of arteries. However, the blind- 
ness of one man makes no way when urged against the 
positive perceptions of another. That which 1 here wish to 
inform the public is, that veins, that is, the two cavas, have a 
good thick covering of red muscular fibre. It appears to be 
continuous with the substance of the auricles. I have not 
been able to investigate the smaller vessels by means of the 
microscope. My late sickness must plead my excuse for 
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