748 
DR. CARPENTER ON THE MUTUAL RELATIONS OF 
seed, everywhere receives the same amount of solar light and heat, whether it be grown 
at the equator or in the temperate zone ; its rate of growth being in a precisely inverse 
ratio to the amount it receives in any given time. Hence it appears that the organizing 
force of Plants bears a relation of equivalence to the Heat and Light which act upon 
them. 
2. This has been separately demonstrated with regard to the special influence of 
Light, in producing the decomposition of carbonic acid and the formation of chloro- 
phyll, &c. ; the amount of carbon fixed by plants being cceteris paribus in accordance 
with the amount of illumination they receive. The influence of Light, it may be re- 
marked, seems to be exerted only in this peculiar process of vital chemistry ; whilst 
that of Heat is exercised in all the other operations in which growth consists ; and 
hence it is that Animals are comparatively little dependent upon light, their food being 
prepared for them by the agency of the vegetable kingdom. 
3. The rate of ‘‘ rotation” of the fluid within the cells of Chara, &c,, and the rate 
of “ cyclosis ” in the latex- vessels of Ficus elastica, &c., appear to be in precise rela- 
tion (within certain definite limits) with the temperature to which these organisms 
are subjected ; the movement of the fluids being accelerated by warmth, and retarded 
or checked by cold*. 
4. In cold-blooded Animals, the same relation may be seen, between the activity of 
the organizing processes, and the amount of Heat to which they are subjected. The 
production of larvse from the eggs of Insects, like the germination of the seeds of 
plants, may be accelerated or retarded at pleasure, simply by the regulation of the 
temperature ; and the time required for the last metamorphosis is precisely in the 
inverse ratio to the heat supplied ; so that, as in the maturation of the plant, each 
individual of the same species receives the same amount of heat, whether the intensity 
of its action be greater or less. Further, it has been remarked by Mr. Paget'^, that 
the processes of development seem to require a higher degree of Vital force than those 
of simple growth ; and it harmonizes admirably with the doctrine here contended for, 
that there appears to be a necessity for a higher temperature for developmental ope- 
rations, than for those of simple increase. Thus in the economy of the Social Bees, as 
shown by Mr. Newport, there is a special provision for generating heat during the 
last few hours of the metamorphosis, in which the tissues and organs of the imago are 
being completed ; and in the Viper and some other ovo-viviparous Reptiles, there seems 
to be an unusual calorifying power, for the purpose of promoting the development 
of the embryo. So, again, it has been found by Dr. Edwards and Mr. Higginbottom 
that the metamorphosis of Batrachia requires a larger amount of light and heat than 
* It would almost seem as if some anti-vital influence, resembling that of “ shock ” in animals, could be 
exerted by mechanical injury on plants. When a portion of the leaf of Vallisneria is detached for the exhibi- 
tion of the movement of “ rotation ” in its cells, the movement generally ceases for some little time ; the appli- 
cation of warmth will usually re-excite it ; and it may then continue for several hours or even days. 
t Lectures on Repair and Reproduction. 
