178 On the BilztionMp exUting [no. 4, xew series,
plementary for the nartare and dcTelopmen: of a superior embryo. I: 15 unrcfssary to compare the Tarious structuTes that are met v:v.z i- : kingdoms, as the results of the transformation of Crll5. I ; find tubnlar tissues formed by the coaleseence
- it-.s. sclerous tissaes where the cells hare been solidified by internal deposit, iT-:=:t. " A : iian Mollosca a considerable quantity of
ce. ..^:;; : 5 per of plants. Indeed one observer relates, thi: ^ . z rcted by chemical reagents in the corpora r. brain; and if we can therefore credit V . . .:l ..zaber headed" will after all have a foundation in truth.
We now come to consider some ©f the functions of organic life, premising that in all organs where these vital operations are car- ried on, we find a true cellular structure retained. Beginning with absorption and assimilation, we fiad these processes varying, ac- cording to the rank of the animal or plant, in the respective kingdoms, but still agreeing in the constant cellular agency. Amongst individuals of humble status, the nutritious matter is at once received through the cell wall by the process of endesmose, to be elaborated and applied in the cavity of the cell to the various wants of the structure. This of all methods is the most simple, and a key to the plans of absorption and assimilation in the higher di- -visions, inasmuch as any apparatus more intricate is merely super- added for the production of a more elaborate nutritious fluid, and its transfer to distant parts of the organism. In the Yertebnta absorption and assimilation obtain in their most perfect state, as we And in this group a distinct tubular system, solely concerned in the manufacture and translation of the chyle or alimentary fluid. Between this and the simple endesmose and assimilation of the ani- malcule, there are many intervening gradations of process, and as an example of an animal occupying an intermediate position be- tween the two extremes, we shall briefly contemplate the internal economy of an Annelide, the Himdo medUinali*. In this creature, nearly the whole of the visceral cavity is filled by the stomach, which consists of an elongated tube with a number of lateral sacs. Over these cscal appendages is spread a delicate net-work of the terminal branches of the circulatory system, destined to receive by
