110 
DR. C. H. JONES ON THE STRUCTURE 
the office of an hepatic apparatus, grounding his opinion on a comparison of the 
secreting elements in the two organs. My own examination of the dorsal appendage 
of the stomach does not lead me to agree with Dr. Williams, in excluding it from 
participating in the function of a liver; I find it to consist of csecal follicles which 
present occasional bulgings ; the diameter of these is about ^^th of an inch ; they 
lie packed together in groups which are easily visible to the naked eye : in structure 
they consist of an homogeneous membrane, which encloses a mass of nuclear granules 
varying in size from 9 - - 4^0 Q - o th of an inch ; also granular globules, oval or circular 
transparent vesicles, yellow amorphous matter and oil-drops ; between these and 
the contents of the gastric caeca I did not observe any remarkable difference ; never- 
theless, I do not mean to imply that the dorsal appendage serves, like the gastric 
caeca, for the reception of the chyle ; but only that, admitting the secretory apparatus 
of the latter may possibly perform the office of producing bile, there seems no suffi- 
cient ground, from difference of structure, for supposing the former to be destined to 
a different purpose. I ought, however, to mention that in one or two specimens I 
examined, the structure of the appendage in question corresponded more nearly to 
the account given of it by Dr. Williams, but this appeared to me to be a deviation 
from the natural condition ; nor indeed have I ever observed anything which could 
lead me to assent to the opinion that it represents a pancreas, an organ which first 
manifests itself unequivocally in the class of Fishes, and exhibits in the different genera 
so many beautiful stages of progressive complication. 
In the Echinidm, another kindred family, we find the alimentary canal, apparently 
of great simplicity, passing from the wonderful dental apparatus on one side, to the 
opposite pole of its elaborately constructed shell, performing only a few gyrations in 
its course; a few salivary caeca are described as entering the canal just before the 
oesophagus commences, but no mention is made of any structure serving the purpose 
of a liver ; I have, however, found in the delicate walls of the intestine a layer of 
elongated follicles, much resembling the gastric tubuli of higher animals ; these 
occupy the whole thickness of the intestinal wall, and are closely in apposition with 
each other; their colour is a deep yellow; they consist of nuclear granules and 
amorphous matter, with probably a yellow fluid ; these materials seem to cohere 
simply together, and not to be contained in tubes of homogeneous membrane ; the 
diameter of the follicle-shaped masses measures about of an inch. If I be cor- 
rect in supposing these follicles to secrete a fluid analogous to bile, it would give 
additional probability to the opinion of Dr. Williams respecting the function of the 
gastric caeca of the Asterias. 
In the class of Annelides we may expect to find the hepatic apparatus in a very 
simple and primitive form, corresponding to the general configuration, which exhibits 
in so marked a manner the law of irrelative repetition. I shall describe the minute 
structure of the hepatic gland in three different instances, where its existence and 
position are satisfactorilyascertained, viz. in the Earthworm {Lumhricus terrestris), the 
