62 



JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



red, 47 ; orange, 48 ; green, 29 ; blue, 49 ; violet, 56 ; and in 

 darkness, 58. 



These results would appear to show that light is less favour- 

 able for the first stage of germination, or sprouting, than darkness, 

 and that, excepting green, which we shall see is always most 

 injurious to plant growth, violet being the nearest approximation 

 to darkness, is better than all the other rays. 



M. Cieslar,* by a series of experiments, came to the conclusion 

 that the influence of light varies according to the species. Thus 

 some, like Mistletoe, do not germinate in the absence of light. 

 Perhaps this may be correlated with the fact that the seeds of 

 the Mistletoe contain chlorophyll in their endosperm. Other seeds, 

 as those of Pistachio, Tangerine Oranges, Peas, &c, contain 

 •chlorophyll in their cotyledons. These perhaps might be also 

 found on experiment to require or to be benefited by light. 



Again, some seeds, as of Barley, Maize, &c, appeared to M. 

 Cieslar to be indifferent to it ; while, lastly, the germination of 

 other seeds was hastened by light. Thus generally small seeds, 

 poor in reserve food, germinated better in light than in darkness, 

 while seeds rich in food-materials either germinate better in 

 light than in darkness, or are indifferent to either. He adds : 

 " One cannot find a single seed which germinated better in dark- 

 ness than in light" — a result quite different from M. Adrian- 

 owski's ; as also is the observation that while yellow rays favour 

 germination, violet rays retard it, and can even render it impos- 

 sible at low temperatures. 



It will be thus seen that these two authors are not altogether 

 in accordance. 



Again, M. Pauchont found differences to occur with diffe- 

 rently constituted seeds. Thus oily seeds appeared to derive an 

 advantage from light. This may be due to the fact that they require 

 a relatively larger amount of oxygen than farinaceous seeds in 

 order to convert the oil into an assimilable substance, and the 

 absorption of oxygen is favoured by light. i M. Pauchon found 

 that this was especially the case with seeds having dark-coloured 

 skins. At the same time the amount of carbon-dioxide given off 



* Ds ¥ Influence de la Lumi&re sur la Germination des Graincs, Ann. 

 Agronomifiues, 1**1, torn. 10, p. -S7. 

 t Ann. des Sci. Nat. liot. x. p. 81. 



I Thus the proportion of O. absorbed under light and in darkness was 

 for Castor Oil as 122 to 04, and for Scarlet llunner as 53 to 37. 



