269 
showing that tho “ sarcode ” of the Protozoa , and the ^pro- 
toplasm ” of plants were essentially identical in their nature. 
Since the publication of Schultze^s well-known works upon 
the Bliizopoda, protoplasm has been studied by a host of 
observers, notably by E. Brticke,* * * § Haeckel, f Kiihne,J Huxley, § 
Allman, || Francis Darwin, If and Beale;** and numerous 
points regarding the place which it tills in the organism have 
been brought to light. 
As before said, it is now universally admitted that proto- 
plasm constitutes that element of the animal and vegetable 
body, with which the essential phenomena of vitality are more 
directly connected, and it is therefore important that we . 
should be acquainted with its more important physical and 
chemical properties. As regards its physical characters, pro- 
toplasm presents itself as a semi-fluid viscous body, trans- 
parent, and either quite homogeneous or minutely granular. 
In no case known to us has the microscope revealed any actual 
structure in protoplasm, and its molecular constitution is, of 
course, beyond all investigation by means of any instruments 
at present available. Though during life usually semi-fluid — 
its precise consistence depending upon the amount of water 
with which it is combined — protoplasm is coagulated by 
exposure to a temperature of about 50° C., and it further 
possesses the singular property of being more or less deeply 
reddened when submitted to the action of a solution of 
carmine. 
Kegarded chemically , we may consider protoplasm as being 
a mixture of albuminoid bodies, or proteine-substances, with 
water, and probably a variable amount of mineral substances in 
addition. It is, therefore, a member of that great group of 
organic compounds which are known generally as the “ nitro- 
genous/' or “azotised" substances; and it may be said, 
roughly, to be a compound of carbon, hydrogen, oxygen, and 
nitrogen, and consequently to more or less closely approximate 
to albumen in its chemical composition. It must be admitted, 
however, that we have no absolutely accurate analysis to fall 
back upon in dogmatising as to the composition of protoplasm ; 
that we cannot assert from positive knowledge that the proto- 
plasm of animals is precisely identical in chemical composition 
* Elementar-Organismen Wiener Sitzungsberichte , 1861. 
t Die Radiolarien, 1862. 
J Protoplasma und die Contractilitat, 1864. 
§ The Physical Basis of Life. Lay Sermons, 1872. 
|| Ann. Nat. History , 1864. 
*[f Quart. Journ. Microscopical Science, 1877. 
Protoplasm, 1874. Also in numerous other works and memoirs. 
