1S37] 



F A R M E R S • IMO f n S T K R. 



2S5 



itiffly, fo piippose tliat ihis eurly waltuit, as well as 

 the syraniores and maples, liiid been pierced too 

 late, and iliaf the spriiii/ flow of their pap was 

 over; or ratlier that, in ihe tlien stale of" tiie at- 

 mos()hore. they evaporated as miicli sap as they 

 received rrnin their roots. 'I^he flow, ol" course, 

 would not au-ain ta!<e jiiace unless i!ie evaporation 

 should be checked by the occurrence of cold wea- 

 ther. This actuallv did occur, the thermometer 

 fdlinir to one degree below zero, followed by a 

 pharp dry frost, when the niapie, sycamore, and 

 walnut trees be^an'to flow, contiimin<; thus till the 

 16ih of Marci), when the flow bcu'an to diminish. 

 JNl. Biot says, ihe etlfct of the cold on the birch 

 tree was verv different, IVut irives no details. 



M. Biot distinctly proved that the sap near the 

 root is less dense, and less rich in saccharine mat- 

 ter, than higher up in the trunk or branches, a fact 

 previously stated by .Mr. T. A. Kuiirht, but ex 

 plained by him to arise li"om the sap in sprintr 

 niinirling with the condensed nutriment deposited 

 in the roots the precedinii autimm. M. Biot 

 thinks diflerently, believinir it to arise from the 

 water}' portion of the sap being, in its ascent, either 

 diffused through the cellular substance, or evapo- 

 rated, or both; and he proved, that, though the 

 eap collected in the phials at different heights fi-om 

 the same tree was more dense and rich, Uie higher 

 it was procured, the portions of wood and bark 

 containinir (he sap gave exactly the same propor- 

 tionsofsaccharine or nutritive matter, at all heights. 



M. Biot fiirther discovered, that the swelling 

 and openino- buds (at least of the lilac) have the 

 power of decomposing the sugar of the sap, and ol' 

 appropriating the carbon contained in it, in the 

 same Avay as he proved the seed-leaves of corn to 

 decompose the fecula contained in the grain, 'and 

 chantre its dextrine into the sugar which nourish- 

 es them. 



Observations on ihe Orowlh and Nutrition of 

 Corn. — M. Biot, findintr that the stow growth of 

 trees was not so well adapted to some of his expe- 

 riments as the quick growth of annual plants, 

 made choice of wheat and rye for observation. It 

 has long been known to physiologists, that, in the 

 process of germination, the farinaceous matter 

 (now known to consist of globules of dextrine in 

 their envelopes) is changed into sugar, which 

 serves tiir the nourishment of the young plant, up 

 to the period when its seed leaves and primary 

 roois make their appearance. But when the sup- 

 ply of nourishment contained in the seed has been 

 exhausted, the young plant must depend on other 

 Eources to maintain its <rrowth; and hitherto it had 

 not been experimentally determined what these 

 othersources of nourishment really are, what mod- 

 ifications they undergo in the various parts of the 

 plant, nor in what manner the different portions 

 are transmitted to the nascent seed in the ear, to 

 nourish and mature it. 



It is important, in all such inquiries, to distin- 

 guish the solid parts, which constitute the frame- 

 work of the plant, fi-om juices or soluble materi- 

 als, which, constantly formed, destroyed, and re- 

 newed, are carried into all the vegetable texture 

 for its nourishment. The first, or solid materials, 

 can be examined by chemical analysis after a plant 

 is dead and dried; but it is different with the other 

 parts or liquids examined by JVl. Biot. 



Rye. — He made his first observations, the 3d of 

 May, on plants of rye already in Ihe ear, but not 



yet in bloom, the period of blooming being still at 

 some distiuice. He treated the roots, the stems, 

 and the ears, each separately, with water, submit- 

 ting them to the proofs of circular polarization, and 

 then he treated the watery extracts condensed, but 

 not to dryness, with s|)ifils of wine; submitting to 

 the proofs of polarization the precipitates as well 

 as the substances not precipitated liom the liquids, 

 in a word, he tried, by addi'ng.to each the yeast of 

 beer, whether thev were susceptible of fermenta- 

 tion, again examining whiMher their rotation was 

 diminished, incniased, or changed in direction. 



The matter from the roots gave traces of an ex- 

 ceedingly fi^eble rotation towards the left; but 

 when it was observed, JNl. Biol had not discovered 

 that a mixture of cane and grape sugar would, in 

 a maimer, neutralize the right and left rotation. 

 The stem indicated a proportion of grape sugar 

 turning to the left, and of (;ane sugar turning to 

 the right, as well as gum precipitated by spirits 

 of wine, and turning to the left with a force 

 similar to gum. Twelve days afterwards, the 

 15th of May, while tfie ear was still far from 

 blooming, the stem presented a mixture of the 

 three substances, but with a considerably larger 

 proportion of cane sjjgar, proved by rotation to- 

 wards the right before being fermented. 



The matter from' the ear on the 3d of May, and 

 before blooming, gave verj^ dillerent results from 

 the matter of the stem; for Mr. Biot could not de- 

 tect in it any sugar, either grape or cane, but only 

 sugar of starch, of which f(3rmentation enfeebled 

 the circular power, without changing its direction. 

 'J'he preci[)itates alsofbrmed by sj)irits of wine, in- 

 stead of having the characters of gum as those of 

 the stem, showed only flakes similar to the en- 

 velopes of dextrine in the mature grain. These 

 results accord with the observations of M. Raspail, 

 who ascertained that, before blooming, the grains 

 of fecula in corn are extremely small, and that 

 their soluble matter is gradually absorbed by the 

 seed organ (ovarium), which it serves to nourish. 

 M. Biot, as yet, found no dextrine. 



After blooming, the composition of the ear was 



found to be very different. The 1.5th of June, the 



young grains of rye taken from the ear, already 



contained globules of fecula containing dextrine, 



j along with some sugar of starcfi, but no trace of 



I cane nor gra[)e sugar. It follows, M. Biot infers, 



1 llmt the cane sugar, the grape sugar, and the gum, 



vvliich are contained in thestemand leaves oi'rye, 



are changed in their nature on passing the neck of 



the ear (/e collet dcs cpis), supplying materials for 



nourishing the young grain, which forms it into 



dextrine and its envelopes. 



IVheat. — In his observations on wheat, M. Biot 

 was more particular than in the case of the rye to 

 keep separate the difl'erent parts of the plant, and, 

 in consequence, discovered difliRrences of compo- 

 siiion, which he could not have beforehand ima- 

 gined. 



The 19th of May, he took young plants of 

 wheat whose ears had not issued from their sheath 

 or hose, he carefully separated the sheathing 

 leaves from the cylindrical stem, and treated the 

 two separately with water, alcohol, and fermenta- 

 tion. The stems, like those of rj^e, presented 

 three carbonaceous substances, namely, grape su- 

 gar, cane sugar, and gum; but subsequent obser- 

 vation showed, that the proportions of these three 

 substaiKies varied much during the progress of ve- 



