26 
almost as universal as gravitation, from the smallest monad to the 
hugest beast, and inhabiting almost every tissue of the body, from 
the liquid blood to the solid bone. It is plain that such creatures 
need be of the simplest structure ; they need no elaborate digestive 
apparatus to prepare their food for assimilation when they are 
surrounded by the ready prepared liquid nourishment of their 
hosts. We find them, for the most part, destitute of heart or 
blood-vessels, secretory apparatus, and nervous system of a rudi- 
mentary kind. On the other hand, on the principle that ‘* Nothing 
grows like evil,” and necessitated by the vicissitudes of their 
changing lives, they have very highly developed organs of repro- 
duction. It is evident any systematic attempt to classify them 
must be difficult, considering the varying circumstances under 
which they live, and the gaps still to be filled up in their hfe 
history. There is one characteristic, however, which they all 
possess in common with one or two other groups of the animal 
kingdom, and that is the possession of a water-vascular system, 
which was noticed in the paper read at our last meeting. This 
water-vascular system is a sort. of representative of a system of 
blood vessels and alimentary canal, the water or fluid in which they 
live performing the offices of the blood. It consists of a number 
of channels communicating with one another cut through the 
parenchyma of the animal, ramifying in all directions, and com- 
municating by one or more apertures with the water outside, some 
of these vessels being contractile, others provided with cilize, by 
means of which they keep the fluid cireulating. By this means 
the great pabulum of all animal life, oxygen, is brought in contact 
with their tissues, and by which, in the same way, nourishment is 
conveyed into the interior and absorbed by the cells. After 
describing the six groups or orders of worms, which he classed 
under the name of Annelida, Mr. Ashby proceeded with a sketch 
of the Ascaris lambricoides, a worm which is common to man and 
his domestic animals, as his first type. It varies in length from 3 
to 12 inches, and its residence is the intestine. Beginning at the 
head, we notice, by means of a lens, three prominent papilla, 
which are uniform in size and moveable during life, and are ~ 
probably suctorial organs, though the animal moves freely about 
in its abode. The oval aperture leads at once into a strong 
muscular cesophagus nearly half-an-inch in length; this passes 
through a slight construction into a straight tube, getting wider as 
it proceeds, and finally ends near the hinder extremity in a narrow 
aperture. No trace of any glands can be found; indeed it would be 
difficult to conceive their necessity in a creature whose food 
requires so slight modification to convert it into its own protoplasm. 
All the tissues of the body appear highly elastic and contractile, 
but the true muscular system consists of four longitudinal bands, 
passing from one end of the body to the other. The nervous 
