208 



FARMERS' REGISTER 



[No. 5 



nists are not arjreeil. The more common opinion 

 at present is, that they can, in the case of dilier- 

 ent genera belon<Tino; to the same natural order; 

 and the experiments of Herbert, Sweet, and 

 others, serve to confirm this opinion. Sweet slates 

 liiat he has piodnced many new <^eraniums in this 

 way. Mr. Knitrht stales," that all iiis attempts to 

 obtain them, proved unsuccessful. Linneeus was 

 of the opinion that they could be produced, and 

 he even went farther, and asserted that they were 

 produced in tlie ordinary course of nature. In a 

 dissertation, entitled •Plantoi Hybridcp,'' he gives a 

 list of 47 such plants, together with the plants 

 ji-om which he supposes then to have been pro- 

 duced. For example, he considers the delphi- 

 nium hybridiim (a peculiar species of larkspur) 

 a hybrid, produced (iom the aconitiim naphellum 

 (wolf's-bane,) and the deljyhinium elatum, (ano- 

 ther species of larkspur.) From the examples 

 given in this dissertation, Linnaeus draws this 

 conclusion: "That only two species of each ge- 

 nus existed ab origine ; and that all the variety of 

 species which now appears, has been produced by 

 the unnatural scattering oi" the pollen of one spe- 

 cies, upon the pistil of another species belonginfj 

 to a dilTerent genus." ' In this conclusion, lie evi- 

 dently goes larther than the facts of the case will 

 jusliiy him. 



Chapter XI. 



COLOn. CHANGES IN COLOR. XAKTHIC AND 

 CYANIC SERIES. ODORS; PERBI ANENT AND 

 FUGITIVE. FLOWERING. 



There is no subject connected with the physi- 

 ology of plants of which so little is certainly 

 known, as tlie causes of the various and ever-va- 

 ryingcolors with which flowersare adorned. "'We 

 see flowers, marked with the strongest contrast of 

 the most dissimilar colors, reproduced with an ex- 

 actness, which is most wonderful. We know 

 that in some plants, without accident, without any 

 visible constitutional change, or any known pre- 

 disposing cause, a yellow flower will become pink, 

 and a pink one yellow; and we know that if the 

 portion of the stem whose flowers have been thus 

 altered, be multiplied by the division of itself, the 

 change is flxed, and maybe continued lor ever. 

 A dingy brownish purple tulip will suddenly, and 

 without warning, burst forth in the most radiant 

 beauty, its dull disagree;ible color disperse, a pure 

 atid spoiless white taking its place, in part, and 

 the brightest and deepest streaks of crimson add- 

 ing richness to iis purity. If we look minutely to 

 these circumstances, we shall find that each par- 

 ticular cell has its own color; that there is no in- 

 termixture of tuits, but that whatever the hues 

 may be, each has its own cluster of cells to repre- 

 sent it ; and even in tlie midst of a large mass of 

 iinifbrrii colorin;;, a few cells, or even a single one, 

 will secrete a coloring matter which forms the 

 strongest contrast with what surrounds it, as in 

 the spotted lily, and similar cases." Respecting 

 the cause to which all these extraordinary circum- 

 stances are to be ascribed, little is known. Still, 

 observation and experiment have put us in posses- 

 sion of some fads respecting this subject, and our 

 knowledge of nature, has enabled botanists to form 

 some conjectures, whieh to say the least, arc not 



improbable. As this is a subject of some impor- 

 tance to the cultivator of flowers, as well aa of 

 considerable interest to every one who attempts to 

 gain an insight into the physiology of vegetables, 

 I shall attempt to give an abstract of what is 

 known respecting it; contenting myself with, sim- 

 ply abridging the account which Prof Lindley has 

 extracted from the writings of De Candolle ; which 

 I would remark, is the only attemi)t at a full and 

 consistent account of the matter, which I have 

 seen. 



We are so accustomed, he remarks, to see 

 plants decorated with the most brilliant colors, or 

 at least invested with the gteen hue, which char- 

 acterizes every scene, that it is not without diffi- 

 culty we admit tlie idea, that such colors do not 

 exist in the plant in its primitive state, but are 

 communicated to it by its own act ; and yet such is 

 the truth. The tissue of plants is, in itselfj com- 

 pletely colorless, of a silvery wl)ite, or of an ex- 

 ceedingly pale yellow ; and the matter contained 

 in the cellules is, with i'cw exceptions, of the same 

 color ; but all is changed when they are once ex- 

 posed to solar light. We are accustomed to say 

 that green plants become white in total darkness. 

 Such, however, is not the liict. Leaves which, in 

 ordinary circumstances, would have been green, if 

 made to grow fi'om the very first in perfect dark- 

 ness, will be white or colorless ; yet leaves which 

 have been once colored never lose their color by 

 being kept away fi-om the light ; if they sometimes 

 appear to do so, it is owing to this : that if the 

 half developed leaves are excluded fi'om the light, 

 they grow larger, whilst no rnore coloring matter 

 is formed, and of course, that which originally ex- 

 isted in the leaf is diluted and spread over a larger 

 space, and thus the color of the leaf is made paler 

 without any of the coloring matter having been 

 destroyed. 



The presence of solar light appears, in ordinary 

 circumstances, to be necessary to the full devel- 

 opement of the coloring matter of plants; and 

 hence it is, that if a leaf be half covered, and half 

 exposed to its action, one part remains colorless, 

 whilst the other becomes green. This is seen in 

 the case of leaves of grass growing out from under 

 a log of wood or any other similar body. The in- 

 tensity of the color is generally proportioned to the 

 intensity of the light to which a plant is exposed, 

 and also to the time for which it has been exposed 

 to that light. The number of white flowers indi- 

 genous to northern regions, is much greater than 

 in equatorial countries. Many flowers, which in 

 the bud, or when but partially expanded, are white, 

 aflerwards become deeply colored. The variable 

 wall-flower (chciranthos chamelis) has a flower, 

 at first of a white color, which afterwards becomes 

 lemon-yellow, and lastly a decided red. Their 

 color seems also, to depend in part, upon the tem- 

 perature to which plants are exposed. The hibis- 

 cus 7mdabilis, a plant of the West Indies, has its 

 flowers white in the morning, pink at noon, and at 

 night red. On the 19th of October, 1828, the 

 flowers of this plant were noticed to remain white 

 all day in the gardens at Havanna. and not to be- 

 come pink until noon the next day. This 19th of 

 October was remarkable lor the thermometer not 

 rising higher than 67" Fahr., whilst the ordinary 

 temperature of the flowering season of the hibis- 

 cus is 850 to 90° Fahr, It was stated that, in or- 

 dinary circumstances, the action of solar light 



