744 
of that capillary plexus, which forms, with the 
convoluted lacteal tubuli, nearly the whole bulk 
of those bodies. The writer is inclined to at- 
tribute it, however, to another agency—the 
Vitalizing influence of certain floating cells, 
which the chyle and the blood contain; and 
the chief points of the evidence of this doctrine 
will now be set forth. 
A comprehensive survey of the vital pro- 
cesses, performed both by plants and animals, 
enables us to bring together a number of ex- 
amples in which ce//s are developed in a tem- 
porary manner, growing, arriving at maturity, 
and then disappearing; apparently without 
having performed any particular function. In 
the albumen of the , for instance, this often 
takes place to a remarkable extent. In the 
yolk of the egg there is a similar transitory 
developement of cells, of which several genera- 
tions succeed each other, without any perma- 
nent structure being the result. In the germi- 
nal vesicle, again (according to Dr. Barry*), 
several annuli of cells are seen to occupy its 
cavity, when it is prepared for fecundation ; 
and the oldest and largest of these contain 
another generation : yet all these disappear by 
liquefaction, as soon as the two permanent cells 
begin to be way ie in the centre. Further, 
in the subsequent developement of all the cells 
which are descended from these, and form the 
' “mulberry mass,” the same process is re- 
peated ; a great number of temporary cells being 
produced, only to liquefy again as soon as 
the two permanent central cells make their 
appearance. It can scarcely be imagined by 
the well-judging physiologist, that all this ced/- 
life comes into existence without some decided 
urpose ; and if we can assign to it an object, 
the fulfilment of which is consistent with the 
facts supplied by analogy elsewhere, this may 
be reasonably considered as having a fair claim 
to be received as a physiological induction. 
In all these instances, and in many more 
which might be quoted, the crude alimentary 
materials are being prepared to undergo conver- 
sion into permanent and regularly organised 
structures. The very first union of the inorganic 
elements into the simplest coer aria 
is effected by the cell-life of plants. The change 
of these principles into the peculiar compounds 
which frm the characteristic secretions of 
plants, is another result of their cell-life. And 
there seems equal ground for the belief, that 
the change of the proximate principles, sugar 
and gum (of which the latter appears to hold 
the same place in the vegetable economy that 
albumen does in the animal), into the peculiar 
glutinous sap, which is found wherever a forma- 
ion of new tissue is taking place, is equally 
dependent 2 > the agency of cells. The 
is probably commenced in the leaves ; 
Bt as the ordinary descending sap, which is 
the product of their elaboration, is not so re- 
markable for its plasticity as the fluid drawn 
from certain rapidly growing parts, it seems 
probable that a local agency takes place in 
these, analogous to that which we shall be able 
* Embryological Researches, third series, 
NUTRITION. 
af 
a 
{ 
to trace in certain conditions of the animal 
economy. Thus, the starchy fluid which is 
contained in the ovule, previously to its fecun= 
dation, is probably not in the state in which it — 
can be immediately rendered subservient to the 
nutrition of the embryo; and the devel 
of successive generations of cells, which exert 
upon it their vitalizing influence, may be rea- 
sonably regarded as the means by which the 
requisite change is effected. Exactly the same 
may be said of the albuminous matter con- 
tained in the yolk of the egg, which is certainly 
not in a condition in which it can be imr 
diately applied to the purposes of nutrition 
and it coteittinn eee regarded as cc 
mencing with the developement of transite 
cells within its own wriyreape. as being 
completed by means of the cells forming the 
ielean layer of the germinal membrane, b: 
which it is subsequently taken up and intro- 
duced into the current of blood flowing through 
the vascular area. A similar pu is pro 
bly answered by the transitory cells develo 
within the germinal vesicle; and by thos 
which appear at a similar period in the evolu. 
tion of the descendents of the “ twin cells 
produced in it. _ 
Many other examples of a similar proce 
might be adduced, but they would all lead t 
the same general conclusion, which harmoniz 
well with the important principle of gene’ 
physiology,—that the higher the grade of str 
ture ultimately to be attained by any part, an 
the more permanent its character is destined t 
be, the longer and more elaborate are the p 
minary stages of its evolution. As an inst 
of this law, which bears a remarkable a 
with the facts just recorded, we may ac 
the production of a temporary respirate 
paratus in the higher plants and anim: 
responding with that which is permane 
the lower parts of the scale. There are pr 
bly cases, however, in which cells are ve 
rapidly called into existence, without that pn 
paratory elaboration of their nutrient mater 
which we regard as due to the vital operat 
of a preceding generation. Thus the B 
giganteum, a large fungus of the 
tribe, has been known to increase, in 
night, from a mere point to the size of a | 
gourd, estimated to contain 47,000,000 
cellules. In such a case it is difficult to” 
pose that any but the most rapid m 
generating cells can have been in opere 
and the idea tbat these could not ha 
developed by any such elaborate proce 
that just alluded to, is borne out by the! 
their extremely transitory character, the 
of such a structure being almost as rapic 
production. The same may be 
those fungous growths in the 
which sprout forth most rapidly, 
apparent exception assists in ing 
We have thas a class of fants 
that the conversion of the chemical com 
into the organizable principle—the aplasti 
the plustic material—is effected in the 
cular situations where it is most wanted | 
vital agency of transitory cell-life ; th 
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