June 2, 1884.] 



THE TROPICAL AGRICULTURIST. 



$09 



all parts of their structure, in the form of salts and organic 

 acids. The same is the case with lime in many instances. 

 The existence of vegetable alkalies in combination with or- 

 ganic acids gives great weight to the opinion that alkaUne 

 bases in general are connected with the development of plants. 

 The ashes of the tobacco plant, of the vine, of peas and of 

 clover contain a large quantity of lime. Such plants do 

 not flourish on soils devoid of lime. By the addition of 

 salts of lime to such soils they become fitted for the growth 

 of these plants; for we have every reason to believe that 

 their development especially depends upon the presence of 

 lime. The presence of magnesia is equally essential, there 

 being many plants, such as the different varieties of beet and 

 potatoes, from which it is never absent. The whole argument 

 suggests that by the analysis of plants we may arrive at 

 a knowledge of their pecuhar wants, and by the chemical 

 examination of soils and manures we may take care that 

 these wants are supplied. 



Whence do plants obtain their principal salt? It has been 

 proved that with the evaporation of salt water salt becomes 

 volatiUsed and dispersed. When sea storms occur the leaves 

 of plants in the direction of the wind are covered with crystals 

 of salt, even to a distance inland of from 20 to 30 miles. 

 But it does not require a storm to cause the volatilisation of 

 the salt, for the air hanging over the sea always contains this 

 substance, and every breeze must carry it away. Now as 

 thousands ^millions) of tons of sea water annually evaporate 

 into the atmosphere, a corresponding quantity of the salts 

 dissolved in it — viz., common salt, chloride of potassium, 

 magnesia, and the remaining constituents of sea water — will 

 b^ conveyed by the wind to the land. By the continual 

 e .-aporatiou of the sea its salts are spread over the whole 

 s urface of the earth ; and being subsequently carried down 

 by the rain furnish to vegetation those salts necessary to its 

 edsteuce. This is the origin of the salts found in the ashes 

 of plants, in those cases where the soil could not have yield- 

 ed it to them. By the foregoing explanations the substances 

 to be found in plants — which is the same to be found in 

 manures and soils on which plants grow — are reduced from 

 things not known to things that are known. In this way 

 persons may feel familiarised with them without a deep 

 acquaintance with chemical science. And it will be 

 seen that in a multitude of cases the practical cultivators 

 of the soil may understand the principles of the science, 

 although ignorant of the precise terms which represent and 

 explain these principles. Thus the housewife proceeds in 

 making bread on scientific principles, although she never 

 saw a book on chemistry, or learned the meaning of a 

 scientific term. 



It what respects does nature present to man the ex- 

 ample of preparing soils? By the gradual processes by 

 which she herself prepares the surface of the earth, in 

 certain instances, for the reception of the higher orders 

 of plants. "What is the common action of nature upon a bare 

 rock which is protruded in any way? You first have some 

 hchens grownng over the surface of the rock. These plants 

 have the power without the aid of anything from the; soil 

 except the mineral ingredients of attracting substances 

 from the air. After generations of these have grown and 

 died, mosses take their place, and grow upon the remains 

 of a kind ot mould which has been made by the decay 

 of the lichens. After the moss hasgro^vn for some years 

 you will find different kinds of natural grasses. These 

 are succeeded by others, until at last you have xipon 

 what was originally a bare rock a soil formed naturally, 

 in which trees can and do grow from seeds naturally sown 

 in it. Take, for example, the lavas ejected from Vesuvius, 

 ^tna and other volcanoes. These lavas, which have been 

 molten and red hot, of course contain no vegetable matter. 

 They have not been long cooled before the wild fig tree 

 and other plants, sending their rootlets into the interstices, 

 spring up and produce abundance of woody matter, which 

 must evidently have been obtained from the air, as it did 

 not exist in the soil. It is clear, then, that there is some- 

 thing in the air which these plants have the power of 

 obtaining; and it is this wliich enables nature to clothe 

 the surface of different rocks with plants of various kinds, 

 so as to present, even when man does not come on the 

 stage at all, a fine scene of foliage wherever moisture and 

 water and other elements of vegetation, can be found. — 

 Lender. 



NOTES ON THE REARING OF SILK-PRODUCING 

 BOMBYCES IN 1883. 



BY ALFRED WAILLY, 



(Jlembre Laureat de la Societe Nationale d'Acclimatation de 

 France). 



{Continued, from page 781). 



The second mode of rearing the Yama-Mdi silkworm in 

 Japan, which is resorted to after the third moulting of the 

 worms, is the following : — I'its are dug one foot wide, and 

 about one foot ami a half deep. These pits are filled with 

 bales of rice, which are well watered and covered with mats, 

 through which oak branches are plimgedto the bottom of the 

 pits. The worms previously bred under cover are now reared 

 in the open air, and uncovered up to the time of their trans- 

 formation on the branches x>hmged in wet rice. The bales 

 of rice receive every day a plentifid supply of water, which 

 allows the foliage to keep fresh for a long time. A\"hen the 

 branches are changed, the old ones are pulled out and placed 

 on mats, in order that no sand or dust should touch the 

 worms, for, if they swallowed any with their food, they 

 would become sick and die. When the old branches have 

 been removed, fresh ones are inserted in their j>laces, and 

 the old ones are then tied or otherwise fastened to the fre.sh 

 branches. 



This mode of rearing has not, as far as I know, been adopt- 

 ed anywhere in Europe or in India, and I do not thiuk it 

 ought to be adopted at all, as the third mode, that of rear- 

 ing on trees, is by far the most simple and the best, especially 

 when the worms are reared on a very large scale. 



Third mode. — Rearing on trees in the open air. This last 

 mode, hke the second, is adopted after the worms have passed 

 their third moult, that is, when they are in their fom-t!i stage. 

 The place chosen is a plantation in the plain in preference 

 to one in the mountain, and the ground, twelve months before- 

 hand, is cleared of all weeds, also of the useless shrubs and 

 trees. ' The branches of the trees wliich are too long are cut 

 down, so that all on which there are worms or cocoons should 

 easily be reached. 



Without going into further details respecting the mode of 

 rearing in Japan, it is certain that if trees were planted in 

 rows, and the branches cut or bent down so as to form a bush 

 eight, nine or even ten feet high, immense quantities of silk- 

 worms could be reared in suitable climates by taking the two 

 following and indispensable precautions: — 1st, to keep the 

 ground clear of all weeds which might harbour insects injur- 

 ious to the worms; 2nd, to have, especially when the worms 

 are large, men to watch the worms constantly, and keep the 

 birds away, as these in a very short time might destroy the 

 whole crop. The worms might be placed on the trees as soon 

 as they are hatched, which would be a great saWng of time 

 and labour, and the rearing would have no other limit but 

 that of the plantation. I will now pass to my notes on the 

 rearmgs of last season. 



Hybrid li&i/lei-FeniJ/i. — On referring to my articles on the 

 rearicgs of silk-producers in 1881 and 1882, it will be seen 

 that I obtained this remarkable hybrid in 1881 by the cross- 

 ing of Uoylei, the Himalaya oak silkworm, with Ferni/i, a 

 north China species. The new hybrid, contrary to what had 

 taken place previou.sIy with other hybrids, was larger and 

 superior in every respect to thejiareut species; its reproduc- 

 tion in 1SS2 from the cocoons obtained in 1881 was most 

 wonderful — many hundreds of fertile eggs from a small num- 

 ber of moths. I then felt most certain that I had created a 

 most valuable silkworm, easy to reproduce and rear. But in 

 1SS3, the third year of the existence of my hybrid, I was 

 cruelly disappointed, for it disappeared entirely. 



Degeneracy was certainly the principal, and perhaps the 

 only cause of this failure. Now, was this degeneracy due 

 to the fact that this new silkworm was a hybrid? I could 

 not to a certainty declare that sucli was the cause, for the 

 Pernt/i silkworms reared at the same time, and imder the 

 same conditions as the hybrid, had degenerated to the same 

 extent; so that it may be that the cause of degeneracy was 

 due to the uufavourable conditions under which the larva's 

 were bred. 



The few hybrid larvre which I reared in London in 18S2 on 

 a small scale, in torrents of rain for the greater part of the 

 time, could not be rehed upon to produce strong healthy 

 pupie. On the other hand, the hybrid cocoons I had from 

 one of my correspondents in Scotland, and those I obtained 



