88 ILLUSTRATIONS OF THE BOTANY OF [ Malvaceae. 
In addition to the information which has been obtained regarding the temperature 
required for the successful growth of cotton, and the notices we have from cultivators 
respecting the soil, it is desirable also to ascertain the degree of atmospheric dryness 
and moisture which is best suited to the formation of cotton-wool. Respecting this I have 
been unable to obtain any information, but there is no doubt that from the extent of 
their distribution, the several cultivated species must be subjected to very different 
degrees of evaporation, and the production of cotton, both as regards quantity and 
quality, must, I conceive, be influenced by this as well as by other causes, particularly 
as we know that the formation of flowers and fruit depends upon the nature and quan- 
tity of the secretions which are formed by the leaves, and in the cotton, probably, by — 
the leaflets of the involucel or exterior calyx. As the density of these secretions 
depends as much upon the rate of perspiration as upon the supply of moisture by the 
roots, it follows that different states of humidity in the atmosphere, checking or exciting 
perspiration, will influence the retention of the fluids in the state of sap, or their 
conversion into concentrated secretions; and as it‘is upon the latter that depend the 
formation of flowers and fruit, it follows that whatever favours the former will be 
useful to the latter; or, as Professor Lindley has well and briefly expressed it, Trans- 
plantation, a dry and heated (and it may be added a rarified) atmosphere, a judicious 
pruning of the extremities of young growing branches, a great decomposition of carbonic 
acid by full exposure to light, or whatever interrupts the rapid flow of the sap, favouirs 
its concentration and the diminution of excessive vegetative vigour, assists the formation 
of flower-buds, and consequently the production of flowers. But a moist or richly- 
manured soil, high temperature, with great atmospheric humidity, a fee and uninter- 
rupted circulation of sap, or a great accumulation ‘of oxygen, in consequence of the 
imperfect decomposition of carbonic acid, have all a tendency to dilute the sap, promote 
excessively rapid growth, the almost exclusive production of leaf-buds, and are therefore 
unfavourable to the formation of flower-buds.  v. Principles of Horticulture, p. 35, 
and p. 54. The same reasoning will apply to the production of fruit and the perfection 
of seed, as well as cotton, and any other accessaries or secretions. 
The degree of moisture and dryness which is best suited to each species, and for the 
production of its several parts and products varies so much, that what is excessive of 
either for one plant, may be just the degree that is requisite for another. What this is, 
can only be known in general from experiment and observation ; and in the present 
case we only know what some cultivators have stated that, according to the’ moisture 
or dryness of a climate, the cotton was long or short stapled, fine or coarse, early 
or ere in flowering, as well as varying in the quantity it bore. There is: no doubt 
considerable differences must exist in this respect between the equability of insular 
Pavates within the tropics, the moist climates of Bengal and Guiana, and the’ mode- 
ration in temperature and evaporation of Georgia and Carolina, as well as of the south 
of Europe. | 
It is generally admitted that the quality of cotton improves in proportion to its vicinity 
to 
