COTTON. 



215 



Ctton. sphere continued, no such fatal event could have taken 

 *— • V"'' place. Hence the causes of the blast of cotton trees ap- 

 pear two-fold, — an excess of vegetation, corresponding 

 with plethora in animals, and exhaustion of vegetation, 

 terminating in a state similar to gangrene : the first fol- 

 lowed by the destruction of the fruit only ; the second 

 by the ahnost total destruction of the plant, which re- 

 covers its health and functions only by pruning and a 

 favourable season. The reasoning of Dr Garnet, as it 

 relates to the last of these diseases, is perfectly applica- 

 ble to the blast of the cotton trees of Demerary. " I 

 am pretty well convinced," says he, " not only from a 

 number of facts which I have myself observed, and which 

 I have stated fully in my Lectures, but also from the 

 observations of Uslar, that blight is almost always a spe- 

 cies of gangrene or mortification, brought on by the ac- 

 tion of the rays of the sun in the spring on the morbid- 

 ly accumulated irritability, which had been produced by 

 a considerable subtraction of heat during the night. A 

 frosty night succeeded by a cloudy or misty morning, 

 is never attended with those effects which ahnost cer- 

 tainly follow, if, when the spring is considerably advan- 

 ced, a frost should be succeeded by a fine warm morn- 

 ing." The difference of temperature in Demerary, be- 

 tween 88° and 70°, suddenly applied to the cotton 

 trees, will produce the same effect, as a frosty night 

 (36°) succeeded by a warm morning (51°) on the fruit 

 trees of the north of England. In both countries, it is 

 the rapidi potentia solis acrior, followed or preceded 

 by the borew penetrabile frigus of Virgil, adurans, or 

 burning, or blasting the trees. Thus heat and cold 

 are relative terms ; and, in the present instance, that 

 degree of the latter which in Great Britain is called 

 frosty within the tropics, is, to our senses, greater than 

 the medium summer heat of the former country ; and 

 that which constitutes what is considered a fine morn- 

 ing heat in the one, would be altogether unsupportably 

 cold in the other ; nevertheless, the power of the cor- 

 responding temperatures in both countries is precisely 

 the same, producing the same mischievous effect. 



There is another cause of blast, which exists in coun- 

 tries circumstanced as Demerary is, and which arises 

 from the structure of the plant itself. I mean the de- 

 struction of the root of the cotton tree, or the injury it 

 receives when, from the circumstances of the situation 

 in which the plant is placed, the root is continually, or 

 for a considerable length of time, immersed in moisture. 

 The cause of injury proceeding from moisture thus ap- 

 plied, is the structure of the root, which is somewhat 

 fusiform or tap-rooted. This is proved by a simple ex- 

 periment. Let several rows of cotton trees be planted 

 on a gently sloping dam or mound of earth, at the foot 

 of which is the water of a ditch or trench, in such man- 

 ner as that the rows shall be gradually elevated above 

 the surface of the water. When the plants have grown 

 to a considerable size, let them be taken up ; and the 

 result shall be, that those nearest the water shall have no 

 tap root, but evident marks of its having been destroy- 

 ed by disease; the next in height shall have a small por- 

 tion of tap root ; and so on to the most elevated, which 

 shall have the tap in a complete healthy state. These 

 plants in their parts above ground, shall exhibit a vi- 

 gour proportioned to the perfect state of the root, and 

 consequently to their elevation from the water. Some- 

 times however, nature, with her usual compensative 

 economy, gives either a new direction to the root, or 

 gives the plant a capacity of receiving from the atmo- 

 sphere, that ©ourisbjaient winch makes up for the defi- 



ciency from the earth, or those remedial fluids which Cotton, 

 counteract the banefid influence of excess of moisture ; "*" "*V"" 

 for, in many low situations, I have known the cotton 

 trees to yield abundantly. 



Before I conclude this part of my subject, I may ob- 

 serve, that a deficient nourishment of the cotton tree, af- 

 ter a long tract of very dry weather, produces an effect 

 in many respects similar to blast. But this effect, in 

 truth, is no more than similar; and the difference is made 

 apparent by the supervention of moderate rains. Here 

 there is no exhausted irritability, no positive hurtful 

 power, but a subduction of the necessary supports of 

 life : moderate nourishment gives l'enewed vigour to the 

 plant, and enables it to yield abundantly. The period 

 from July to November 1801, afforded a striking illus- 

 tration of this ; scarcely any rain fell during the whole 

 of these months, whilst the chenille devoured the leaves, 

 leaving the stem and branches completely striped until 

 September, and very little cotton was produced. Is 

 November, moderate showers recovered the cotton trees ; 

 and the heavy rains of December, instead of injuring 

 them as they did the preceding year, gave them a great 

 addition of health and strength, and enabled them to pro- 

 duce most abundantly. This is proved by the cotton 

 picked during these months ; in October 70531b. in 

 November 13,8£61b. in December 53,972 lb. This was, 

 in fact, among vegetables, a case correspondent to that 

 of famine, or accumulated irritability among animals, so 

 finely illustrated in the ingenious remarks of Dr Thorn- 

 ton on the state of the crew of Captain Bligh's boat, 

 (Med. Extracts, vol. iii. part 3. sect. 44.) 



In the consideration of the pathology of plants, we 

 are much assisted by bearing in mind the analogy^ 

 which may be perceived between the diseases of plants 

 and those of animals,~abranch of agricultural knowledge 

 of very high importance, but in which it must be con- 

 fessed hitherto little progress hath been made. The 

 causes, symptoms, and cure of both, come under the 

 general principles of medicine ; and by applying these 

 principles, as they relate to the latter, to the former, we 

 shall find an unexpected facility in the developement of 

 the ratiocination on which their prevention and cure 

 depend. Thus, if the disease of the plant proceeds 

 from plethora, depletory means may go far to cure it ; 

 if the disease arises from direct debility, the gradual ad- 

 mission of stimuli, or of those means suitable to the 

 nourishment of the plant, will effect the restoration of 

 its vigour ; but if, on the other hand, the disease is 

 gangrene or a state of exhausted irritability, we must 

 submit ; and our exertion then must be directed to pre- 

 serve the trunk and larger branches, and prepare them 

 for a new growth, or a renovation of their vegetative 

 powers at a future season, for the means of immediate 

 recovery are not in our power. I have said, that the 

 excess of the excitement of the cotton tree, proceeds 

 from a redundancy of moisture or water; the cure 

 therefore, is evidently the quick discharge of that water, 

 by the enlargement of the sluices or outlets of the plan- 

 tation, or by having, what is called in Demerary, a deep 

 drainage. Should circumstances prevent this from be- 

 ing immediately effected, which often happens, owing 

 chiefly to the nature of the soil, it is, at least, in the 

 power of an active and judicious planter to prevent the 

 recurrence of the evil. Besides the usual means of 

 deepening the channel into the sea, and fencing the 

 windward side of it against floating mud, and putting in 

 larger kokers or flood-gates; there is another, which, 

 without due attention to the operation of it, may be 



