394 Proceedings of Royal Society of Edinburgh, 
in describing some observations on the Cyanosis of Congenital 
Heart Disease, in The Lancet ,* an explanation of the manner in 
which cyanosis is produced was advanced by me. From that 
paper it seems advisable to quote the hypothesis to which my 
observations led me : — 
“ Starting with the conception that cyanosis is produced by 
obstruction to the circulation and venous stasis, the question now 
arises why this condition should be associated with an increase in 
the number of the blood-corpuscles. It is not only in the cyanosis 
of congenital lesions that the increase is found, but in all cases 
where cyanosis is really present on account of failure of the cir- 
culation. To this point Toeniessen and Schneider have particularly 
called attention, and of the accuracy of the observation anyone can 
convince himself by investigation of the blood. The work of 
Malassez seems to show that the blood in the superficial parts of 
the body contains a larger number of red corpuscles than that from 
the deeper layers, and Penzoldt and Toeniessen believe that this 
increase is caused by the loss of fluid from the surface, while the 
blood of the interior is constantly receiving fluid from the alimentary 
canal. Even if this be correct, it cannot be accepted as an explana- 
tion of the great increase in the number of the corpuscles found 
in cyanosis, as it would involve the postulate that in some cases 
where the number of corpuscles is nearly doubled the quantity 
of the fluids of the blood must be reduced nearly to one-half. 
Cohnheim’s celebrated experiment of tying the crural vein of the 
frog, which is followed by a considerable increase of the corpuscles 
in the vessels, with the transudation of serum into the surrounding 
tissues, may be regarded as an explanation of the moderate increase 
in the cases accompanied by anasarca, but it has no special bearing 
upon cases of congenital cyanosis in which there is no drain of fluid 
into the tissues. It may possibly be held that in such cases the 
lymph vessels are unusually active and that the fluid constituents 
of the blood are as rapidly absorbed as they transude. Such an 
opinion can scarcely be seriously entertained. The backward 
pressure on the venous system which causes the transudation must 
tell on both terminations of the absorbents. It may be admitted 
freely that the increased pressure on the peripheral veins may tend 
* The Lancet, vol. i., 1895, p. 24. 
