60 Transactions of the Royal Microscopical Society. 
mains hardly a chemical reagent, liquid or gaseous, to the influence 
of which they have not been subjected. Heat, moisture, as well as 
electricity in its diflerent forms, have been applied. The changes 
occurring in their substance by the action of all these reagents, 
have been closely watched, and many deductions relating to their 
structure have been made. 
An enumeration of the most important of these experiments will 
be found in Kollett’s article “ On the Blood,” in Strieker’s ‘ Hand- 
huch der Lehre von den Gewehen, &c.,’ as well as in other treatises 
on this subject. But it is certainly strange that while great im- 
portance has generally been attached to the various changes 
occurring in the form of the blood-corpuscles by the action of the 
particular reagent (which, after all, are only due to a contraction 
or coagulation of their protoplasm), the double contour of these 
bodies, the only proof of the presence of a membrane, whether pre- 
existent or artiticially produced, is scarcely mentioned, and appears 
to be generally overlooked or ignored. 
In my treatise ‘‘ On the Origin and Development of the Coloured 
Blood-corpuscles in Man,” published in the February number, 1874, 
of the “ Monthly Microscopical Journal,” I made some casual remarks 
in reference to the fine double contour observed in the human 
coloured blood-corpuscles after being deprived of their colouring 
matter by the simple action of that most neutral agent, water. On 
these stomata, then, as Kollett would call the altered corpuscles in 
question, a delicate double contour is always detected l)y close 
inspection. In directing attention to this double contour, however, 
I do not presume that its presence indicates a pre-existing true 
cell-membrane. But, as I have remarked in the above-mentioned 
article, I do suppose that the coloured blood-corpuscle of Man at 
maturity undergoes a slight condensation on its surface in the form 
of a thin layer or pellicle, which, resisting the solvent power of 
water, finally appears in the form of a double contour. To these 
conclusions, E. Bay Lankester had also arrived, from a series of 
observations which he made on the coloured blood- corpuscles, with 
regard to the action of gases and vapours. The results of these 
observations were published in the October number, 1871, of the 
‘ Quarterly Journal of Microscopical Science.’ “ The red blood-cor- 
puscle of the vertebrata,” he says in his summary, “ is a viscid and 
at the same time elastic disc, oval or round in outline, its surface 
being differentiated somewhat from the underlying material, and 
forming a pellicle or membrane of great tenacity, not distinguish- 
able with the highest powers (whilst the corpuscle is normal and 
living), and having no pronounced inner limitation.” 
Lankester, therefore, regards the coloured blood-corpuscle as a 
viscid and elastic disk, which of course implies that its substance is 
homogeneous or without structure ; he further supposes its surface 
