Vol. XII. No. 287. 



THE AGRICULTURAL NEWS. 



13T 



The French Antilles and the Panama Canal. 



In an ;iiticle entitled Le C';inal de Panama et nus 

 Colonies, which appears in L'c.ijiansion C'oloniale for 

 Jlarch 19l:{, reference is made to certain projects for 

 improving the harbours of ilartininne and (liiadeloiipe, 

 in view of the increase in the shijijiing trade between 

 Europe and Central America, that will take place' in 

 1!)1.5 on ihe completion of the Panama Canal. 



. It is asserted from the evidence obtained in 1912 

 bv the French Commission sent by the Covernment to 

 investigate that countrys colonial ports of call, that 

 there is no occasion for the creation of a coaling station 

 or provision port because of the uroxiniity of the islands 

 to Panama, and because of the fact that the pons in 

 question do not lie on the direct route. Nevertheless 

 the Commission was of opinion that it would be 

 desirable to improve the harbours in response to the 

 needs of the Colonies themselves and iheir ngular 

 development. A nroject to deepen the anchorage at 

 Pointe-a-Pitre to allow steamers to go alongside the 

 wnarf, is estimated to cost three and half million francs. 



The Periodicity of Tropical Plants. 



The above subject has recently received attentioo: 

 by Klebs, whose investigations have been made to> 

 ascertain (1) whether the growth of tropical plants is 

 on the whole periodic and (2) whether the periodicity 

 so far as observed in the Tropics is a constant character 

 or is capable of being modified by varying the condi- 

 tions. The work is described in the Experiment Station 

 RecorJ ior January 19 Hi from which the present note- 

 has been abstracted. Leaf fall was the chief character 

 investigated, and in a number of tropical species it was- 

 found to occur non-periodically, but some plants, 

 become periodic in this respect after they are old- 

 Uther plants were found to cast their leaves, apparently 

 in response to changes in environment, at a time whert 

 normally they would not do so: still other species^ 

 according to variations of nourishment, cast their leaves 

 all at once or only gradually through a long period. 



In Java and Ceylon similar observations by Volkens 

 led to the conclusion that no general connexion can be- 

 regarded as established there between leaf fall ancS 

 climate. 



Wild Silk Cocoons from Mozambique. 



The Jornal iV Aqricultara tla Cmnpanhid de Mo- 

 r^niihiquc, Vol. li, No. 2, contains a rejjort on a sample 

 f cocoon?, the product of a species of Anaphe, sent for 

 examination to the Imperial Institute. The sample 

 ■was collected in the forests of JIadanda and Mafuci and 

 appeared to be similar to the Anaphe silk obtained in 

 Southern Nigeria. 



In the examination, six of the nests were cut up 

 and sorted into three grades; (1) the outer layers con- 

 sisting of the paper-like covering and the loose-textured 

 silk beneath it; (2) the parchment- hke layer and (8) the 

 rocoons. Fair samples of each grade were taken for 

 xamination and were submitted to the 'boiling off' 

 process with (a) 'i per cent, sodium carbonate solution 

 and (b) o per cent, soap solution. The results obtained 

 were as follows: (i) loss in outer layers after treatment 

 in (a) and (b) for one hour, 2."J per cent, (expressed on 

 the dry silk): (2) loss in parchment-like layer after two 

 liours treatment, 18-.5 per cent.; (o) loss in cocoons after 

 . -hour treatment, 29-4 per cent. These losses on boil- 

 ing off were rather high comjjared with those obtained 

 v.ith samples of Anaphe silk from Southern Nigeria 

 and Uganda. 



It is stated further that the c.icoons are too loose 

 in texture to allow the silkte be wound otf' or reeled, as 

 is done in the case of the mulberry silks. It is possible, 

 however, by carding and combing to convert the whole 

 of the silk, both from the external layers and the 

 cocoons, into 'spun' silk, which could be used for 

 manufacturing purposes if obtainable in large quan- 

 tities and at a sufhciently low price, Crude nests of 

 Anaphe from Uganda, of somewhat superior quality, 

 have been stated to be worth 4J,c?. per Ifi. in the 

 United Kingdom. 



Effect of Drainage on Rice Soils. 



Interesting results are recorded in the Agricul- 

 tural Joiirnal of India for January 191o, the outcome^ 

 of a series of pot cultures of rice plants of the same? 

 age and variety made with the object of ascertaining: 

 some of the soil conditions under which a disease of rice? 

 called Ufra, is likely to occ\ir. In the different series,^ 

 half the pots had the tubulure at the base plngged to 

 prevent drainage; in the remaining half this was lefts- 

 open. The most interesting results w-ere obtained by 

 the addition to the pots of oil cake (at the rate of 

 00 lb. N per acre). After thirty-two days' growth, all th& 

 plants (drained and undrained) so manured had turned 

 brown and appeared withered and moribund. The 

 effect appeared to be due to a direct toxic action of 

 the products of decomposition of the cake; laboratory 

 experiments at the same time showed that no nitrifica- 

 tion w^as going on in the saturated undrained soil, buti- 

 that certain anaerobes were producing foul-smelling: 

 decomposition products such as indol, and gases 

 including nitrogen, marsh gas and carbon dioxide. In: 

 the drained soil the toxic products were quickly carried! 

 away which resulted in the rapid recovery and eventuaL 

 good growth of the plant?. Those in the undrainfedi 

 soils never properly recovered. The addition of oil- 

 cake was found to produce greatly increased tillering. . 



In the undrained pots, the root development below 

 soil level left the original long stem of the transplanted 

 seedling with a bunch of roots at its lower extremity- 

 in the drained pots, howe\ er, the lower part of the stenv 

 rotted away, leaving only the upper half with a muclt 

 more fully developed bunch of roots. In other words, the- 

 deeper root system was found to occur in the undrained/ 

 soil which is contrary to what would be expected. Thi.s. 

 curious phenomenon is explained by the fact that, in all 

 {uobabiliiy, the plants in the undrained soils were- 

 almost entirely dependent upon anaerobic food, which, of 

 course, v^-ould be most abundant at the bottom of the pot> 



