CARTER, ON THE COLOURING MATTER OF THE RED SEA. 179 
tensible inner membrane gave way, and permitted an extra- 
vasation of a portion of the cell-contents between it and the 
outer membrane, its own continuity being in the meanwhile 
instantaneously restored by cohesion of the ruptured borders.* 
In this way a microscopic drop of the cell-contents would be 
lodged between the outer and inner membrane, and com- 
pletely severed from the general cell-cavity. The peculiar 
modification spoken of as the ‘‘ hooded’? appearance might be 
due to imbibition of fluid between this microscopic drop and 
the outer envelope. 
The chief difficulties in the way of this explanation arise 
out of the differences of nature which appear to exist between 
the projection and the general cell-contents of which it is 
supposed to be a detached portion. The projection refracts 
light much more highly than the cell-contents; it also is 
deeply dyed by magenta, whereas the cell-contents are only 
very feebly so. 
In conclusion, it may be added that important advantages 
may be expected from the use of magenta in histological 
researches. Its inert chemical character, its prodigious tint- 
ing power, and its sohubility in water, eminently fit it for such 
a purpose. It will probably prove of especial use in bringing 
into sight objects which otherwise evade the visual organs 
from their absolute colourlessness and transparency, and from 
the equality of their refraction with the medium in which 
they exist. 
Nore on the Corourine Marrter of the Rep Sea. 
By H. J. Carter, F.R.S., &c.t 
To those who have sought for all that has been published 
on the colouring matter of the Red Sea, it will be well known 
that the excellent memoirs on this subject by M. C. Montagne 
in 1844, and M. C. Dareste in 1855 (both in the ‘Ann. des 
Se. Nat.,’ the former in sér. 3 (“ Bot.’”’), t. ii, p. 331, and the 
latter in sér. 4 (“ Zool.’’), t. iii, p. 179), are the most elaborate. 
* In the same manner as a soap-bubble, when bisected, instead of coi- 
lapsing, forms, in virtue of the adhesiveness and fluidity of its envelope, two 
new and perfect bubbles. That the cell-wall of the blood-dise possesses 
some such endowment seems highly probable. I have on several occasions 
witnessed, after adding magenta, the total extrusion of the nucleus, both in 
the frog and in the newt, without the least collapse of the corpuscles. 
+ Uxtracted by permission from the ‘Annals and Mag. Nat. Hist.,’ 
March, 1863, vol. xi, p. 182. 
