736 
DR. CARPENTER ON THE MUTUAL RELATIONS OF 
spontaneously in some cases, and to be an excited phenomenon in others, thus com- 
bining the characters of both classes of movement, and showing their dependence on 
similar properties of the contractile cells. 
Further, in many of the higher plants, and also in animals, we witness movements 
of fluid through a capillary network, which must be wholly or in part due to the vital 
relations of the fluid and the tissues through which it is carried; no physical agency 
being capable of entirely accounting for these movements, and some of them taking 
place under circumstances, which, as in the case of the rotation within the cells of 
the Chara, &c., seem to exclude the idea of such agency. Thus the cyclosis of 
Schultz (a recent observation upon which, apparently free from all fallacy, has been 
recorded by Prof. Balfour, ‘ Manual of Botany,’ p. 128 ), whether or not an universal 
phenomenon, seems unquestionably to present the spectacle of a rapid capillary cir- 
culation, not maintained by any vis a tergo, but depending upon forces connected 
with the vital endowments of the parts through which it takes place. The movement 
of nutritive fluid in the canals excavated in the tissues of many of the lower Animals, 
in like manner, seems to be but little dependent on mechanical propulsion, and to 
be chiefly maintained by some power originating in the living tissues. And even the 
capillary circulation of the highest animals, in which the regular flow is sustained by 
the propulsive power of the heart, exhibits certain residual phenomena, — such as local 
accelerations and stagnations, — which cannot be attributed to changes in the rate or 
power of the heart’s contractions, and indicate the existence of influences arising out 
of the vital relations of the nutritious fluids to the tissues through which its move- 
ment takes place ; — this movement being most active w’hen the formative actions of 
the part are being most energetically performed, and exhibiting a retardation as soon 
as any influence depresses them*. 
The forces concerned in the growth, development, and movements of Animals appear 
to be essentially the same with those whose existence has thus been traced in plants. 
The animal, however, deriving its nutriment from organic compounds previously 
elaborated, does not perform that preliminary operation, which is so remarkably inter- 
mediate between chemical and vital agency, viz. the production of ternary and qua- 
ternary compounds, of complex atomic constitution, by the union of their elements. 
But in animals we find an additional power, termed Nervous Agency, nothing analo- 
gous to which exists in plants ; this power, related on the one hand to the conscious 
mind, to which it communicates impressions derived from the external world, is also 
related, in a very remarkable manner, to the vital endowments of the organism in 
general, as will be presently seen, and particularly to the contractile tissues ; the most 
perfect form of which (the striated muscular fibre) is usually called into action 
through its instrumentality, in obedience to mental impulses. 
* That such is the case, must be admitted, the author believes, by all Physiologists and Pathologists who 
study the phenomena of the capillary circulation, whether or not they be disposed to admit the validity of the 
hypothesis of “ vital attractions and repulsions ” which has been offered by Prof. Alison as an explanation of 
this order of phenomena. 
