ORIGINAL COMMUNICATIONS. 
The Anatomy of the Eartuworm. 
By E. Ray LanxKester. 
Parr IIT. 
In the present number of the Journal the hemal and 
nervous systems of the earthworm remain to be described. 
No special respiratory organs can be indicated. The processes, 
therefore, of the oxygenation of the blood and tissues will be 
considered in connection with the hzmal system. 
Hamat Sysrem.—In the earthworm, as in other Annelide, 
there are two fluids, each of which has claims to rank as 
“blood.” One of these fluids is red and free from corpuscles, 
and contained in a very extensive series of vessels; the other 
is colourless and transparent, abounding in nucleated cells 
and corpuscles, and occupies the general or perivisceral cavity 
—the space intervening between the digestive tube and the 
muscular parietes of the body or integument. It is obvious 
that the latter corresponds to the fluid contained in and 
circulated by the heart of the Insecta and Crustacea, as has 
been shown by the researches of De Quatrefages. It is no 
less evident, as Professor Huxley has suggested, that the red 
vascular fluid is homologous with the water-vascular system 
of the Turbellaria, Trematode worms, and other Scolecida, 
which again appears in the Echinodermata as the ambulacral 
system, communicating with the exterior in the Echinidea 
and Asteridea, but definitely closed in the Ophiuridea, ; 
Crinoidea, and Holothuridea. The two fluids of the Annelid 
are represented still lower down in the scale of creation by 
one, as that contained in the somatic cavity and canals of the 
Clenophorous Actinozoa, which gives evidence of its homolo- 
gies with the ambulacral system of Echinoderms by its 
relation to the tentacular processes, and with a nutrient 
system, such as that of the Asteropods by its intimate con- 
nection with the contents of the stomach. Thus, then, we 
VOL. V.—NEW SER. ul 
