624 
DR. T. WILLIAMS ON THE BLOOD-PROPER AND 
the apparent continuation of this inference, that what is true of the young is so also 
of the old. In relation to the history of the solid elements of the chylaqueous fluid 
in the Annelids, another fact of equal value and significance with the former may 
here be mentioned. For some time before the death of the old worm, whether the 
death take place by fission of the body into fragments, or by general decay and 
decomposition, the corpuscles of the chylaqueous fluid go on gradually disappearing. 
The ova and sperm-cells accumulated in the fluid of the visceral cavity during the 
season of reproduction, also supersede, to a great extent, the proper corpuscles of 
this fluid. At this period however the blood-system acquires a very conspicuously 
augmented development. 
In studying the histology of the solid elements of the fluids in the Invertebrata, it 
/ is desirable to forearm the observer with one admonition. When these bodies dehisce 
‘ under the eye in the field of the microscope, the semifluid contents are projected out 
in strings or filaments ; the highly fibrinous fluid contained in the cells coagulates 
as it escapes. This appearance has deceived some observers into the supposition that 
such cells are ciliated, epithelial, self-motive bodies. They are not so. I have 
ventured to estimate this frequent fact as a direct demonstration of the theory advo- 
cated by some physiologists, that the floating cells of the fluids secrete a self-coagu- 
lating principle. But at the present stage of this inquiry the question admits of no 
reply, whether the mode indicated is the only process by which fibrine is generated in 
the living fluids ? It is probably not so. My present conviction is that fibrine, at all 
events in the vital fluids of the invertebrated animals, may be evolved in a non- 
corpusculated fluid, in virtue of a zoo-chemical process enacted by the liquid jaer se. 
Let us now proceed to a detailed description of the corpuscular elements discover- 
able in the chylaqueous fluid of the principal families of the Annelida. 
In Arenicola Piscatorum the chylaqueous fluid is very abundant ; the cavity in 
I which it is contained is scarcely at all partitioned by segmental septa. The floating cells 
E of the fluid in this worm are relatively numerous and very liable to dehisce, producing 
digitate, fibrillated, ciliated, stellate and other forms of bodies. These accidental 
appearances must be discriminated from the entire unbroken cells (fig. 14). These 
latter are orbicular in figure, bearing a nucleus and filled with minute granules. They 
are very liable to cohere together into round agglomerated masses (fig. 14 a). As the 
process of evaporation proceeds crystals of chloride of soda appear (fig. 15). In the 
young Arenicola the peritoneal fluid is less abundantly corpusculated and colourless 
(fig. 31). In the old animal also the corpuscles disappear. During a considerable part 
of the summer ova and sperm-cells abound in this fluid ; they should be carefully distin- 
guished from its proper corpuscles. In Arenicola the blood-proper is exclusively 
aerated. The integuments bounding the visceral chamber are too dense to admit of any 
agency of the surrounding medium on the fluid contained within. Under such circum- 
stances the physiologist must admit one of two suppositions. The chylaqueous fluid, 
being a vital Jluid, must in some manner be oxygenized. In this case this can happen 
