Vol. XTII. No 422. 



THE AGKICULTUKAL NEWS. 



•207 



fibre enveloping the seeds is used for the same purpose of 

 stuffing pillows and mattresses as the fibre of the silk-cotton 

 tree {Eriudendroii iinfnnfi/osi/w), wliicli is the kapok of 

 commerce. 



In some of the drier islands, such as Antigua, where, so 

 far as the writer of this note knows, the cork tree does not 

 grow, the wood of another tree is used by fishermen for the 

 same purpose. This tree is the swamp or monkey apple 

 (^Anoiiapalustris). It is a small tree seldom growing more 

 than 20 feet high, the trunk being from 10 to 12 inches in 

 diameter. The wood is very light and soft, ami is said to 

 be used in Porto Rico for making rafts. Cook and Collins 

 give the .specific gravity of the roots as 0'175. Besides being 

 used for the making of floats for fishing nets, the wood is 

 sometimes employed for sharpening razors. 



Although not nearly as light as the wood of thr two 

 trees above mentioned, the silk-cotton tree aiibrds a very soft 

 and light wood which is said to be rather strong, and to resist 

 water moderately well. It is stated that canoes are some- 

 times made from the enormous trunks or huge branches of 

 this tree, but that such canoes are not very durable. 



Another common tree of the West Indies is Biiisera 

 _gummifera, the turpentine tree, or gommier rouge of the 

 French islands. It grows to a considerable size, and seems 

 especially to like limestone districts. The wood of this tree 

 is also very soft and light, and is also said to be used for 

 making canoes. 



Two species of Spondias. the golden apple (5. Jit/iis) and 

 the hog plum (S. hiha) are common throughout the West 

 Indies. The trees of both of these species attain a consider- 

 able size in height and diameter of trunk. The wood of both 

 -of them is also light and soft, but is not used for any purpose, 

 as far as the writer of this note knows. 



The breadfruit tree {Artocarpus incisa) also furnishes 



^ yellowish-grey wood rather light and soft, but strong, 



resistant, and elastic. These trees are, however, altogether 



too valuable as food producers to be cut down to supply any 



large nuantity of timber. 



The obtaining of any large amount of a given kind of 

 timber from West Indian forests is a matter of difficulty, 

 owing to the fact that there is very seldom a collection of 

 the same species growing together in one neighbourhood. 

 Suoh trees, however, as the cork wood and the monkey apple 

 are found more or less in groups along the banks of rivulets, 

 in the case of the cork tree; or in swampy land, in the case of 

 the monkey apple. 



The possibility of the employment of the huge flower-stalks 

 of the various species of Agave for the construction of rafts 

 ,niay be noticed in connexion with the use of very light woods. 

 These flower-stalks are regularly used for this purpose by the 

 fisher folk in some parts of An'.igua. In several islands it 

 would be possible without much difficulty to collect large 

 cumbers of these. 



THE BEHAVIOUR OF SWEET POTATOES 



IN THE GROUND. 



In some investigations on the behaviour of sweet 

 potatoes in storage by Messrs. Hasaelbring and Hawkins, of 

 the Bureau of Plant Indu-try, United States Department of 

 Agriculture, recorded in \.\ie Joi/n-'i/ of Agnai/tiiral Research, 

 Vol. III. p- 331, and noticed in the Agricidfiiral AW's, 

 Vo'.. .\IV, p. 140, it was observed that the percentage "i 

 starch was always highest, and the percentage of sugar 

 lowest, in freshly dug potatoes. The c.^nstancy of the con- 

 ■ dition seemed to justify the conclusion that, in the growing 



sweet potato the reserved material etists essentially in tha 

 form of starch, and that the appearance of sugar in consid- 

 erable <juantities occur? only in storage, or after the destruc- 

 tion of the leaves. 



In order to determine whether these quantitative 

 relations between the starch content and the sugar conteni^ 

 of the sweet potato remain constant throughout the latter- 

 part of the growing season, an^l to what extent they ara» 

 changed by the death of the vines, Mr. Hasselbring conductecL 

 a further series of experiments on sweet potato roots from^, 

 ihe time they were large enough to furnish the requisitae- 

 samples, until the} were seriously damaged by frost. Thes 

 results of these e.xperiments are recorded in the journal o^ 

 Agriiultiind Resianii, Vol. XII, No. 1. 



This record of the condition of sweet potatoes during thee, 

 period of growth may be useful as an aid in determining that. 

 time for harvesting the crop. Mr. Hasselbring advisea. 

 growers, as a rule, to dig sweet potatoes when they are fully 

 matured, or after they have thoroughly ripened. While it isL. 

 implied that the roots reach a more or less definite stage of 

 ripeness, the characteristics by which this state may be recog- 

 nized are not precisely defined. 



After giving detailed descriptions and tables of analyse* 

 made after various periods of growth of the root, Mr. Hassel- 

 bring comes to the conclusion that the changes occurring in 

 sweet potatoes in the ground during the latter part of the grow- 

 ing season proceed in a regular and orderly manner. During- 

 the latter part of the period of growth the composition of tha- 

 roots remains remarkably uniform, and presents no striking- 

 on irregular fluctuations. During this period the root is. 

 characterized by a high starch content and a low sugar 

 content. The changes which occur later are associated with, 

 the death of the vines. Prominent among these changes i*. 

 the accumulation of water in the roots as a result of the 

 cessation of transpiration, in consequence of the destruction- 

 of the leaves. With the termination of the flow of materials 

 from the vines, the carbohydrate transformations charac- 

 teristic of sweet potatoes in storage are inaugurated. Thes6= 

 changes consist in the transformation of starch into sugars. 

 Appreciable destruction of carbohydrates does not appear to- 

 occur in potatoes in the ground until after the roots hav& 

 been injured by frosts. 



The changes here spoken of have a practical bearing on 

 the question of maturation of sweet potatoes, and the best 

 period of harvesting them. Since the carbohydrate relatioa 

 of the roots in the ground remains practically unchanged 

 while the vines are uninjured, the roots cannot be said to- 

 undergo a definite process of ripening, in the sense of a pro- 

 gressive transformation of one reserve" substance into 

 another, such as the change of starch into cane sugar and 

 invert sugar in the ripening apple. Under ordinary condi- 

 tions sweet potatoes continue to grow, without reaching any 

 definite state of maturity recognizable by progressive change 

 in the reserve material which they contain. The choice of 

 time of harvest, therefore, is not a matter of maturity of the 

 roots, but is governed by other factors. In the United 

 States sweet potatoes may safely •be kept in the ground 

 until the leaves have been injured by frost. 



(Jf the changes which occur after the destruction of t'l* 

 leaves, the accumulation of water in the roots deserve* 

 consideration. It can scarcely be doubted that this increased 

 water content is detrimental to the successful storaae of the: 

 root", and causes them to be more sitbject to decay than rootst 

 of normal water content. iJn this accoitot it is of utmost 

 importance that the harvesting Orf swfet jjofatoes be not long 

 delayed after the leaves liive been killed. 



