596 Pri7iciples of Gardening 



the latent buds, or germs, which exist in the axils of the leaves 

 are rarely called into action : while in bulbs, the corresponding 

 germs are very frequently developed in the form of little bulbs, 

 which appear on the margin of the root-plate. The same germs, 

 or latent buds, when they exist in the axils of the flower buds, 

 appear to become ovula, and after fructification to change into 

 seeds. These metamorphosed bulbs appear either singly or se- 

 veral together ; and, in the latter case, they are sometimes, as in 

 yi'llium sphaerocephalum, seated on a long bundle of vessels, 

 which looks like a filiform pillar, and in its developement shows 

 some analogy to the umbilicus of seeds. I am of opinion, 

 therefore, that these ovula and the offsets are both produced by 

 a change in the rudiments of the bud ; and that the offset and 

 the seed are at first similar structures, but that, from the various 

 changes they undergo, they are transformed into differently 

 organised parts, which, however, in their functions bear a great 

 resemblance to each other. As a proof of this may be men- 

 tioned the transformation of the ovula, after imperfect impreg- 

 nation, into bulb-buds, as in t/uncus supinus and Poa bulbosa ; 

 or into bulb-tubers or corms, as in Pancratium, Crinum, Ama- 

 ryllis, &c. The latter, however, never happens when the plants are 

 artificially impregnated ; and when we think we perceive an em- 

 bryo in these growths, it consists only of the already formed young 

 shoot of the tuber, which is surrounded by the thick testa. The 

 succeeding stages of growth prove this ; as the plant is developed, 

 not like a monocotyledonous seed, but like a bulb-tuber or corm. 

 In the seeds of the Orchidaceae, also, a very remarkable pheno- 

 menon is observable. They have a testa of very delicate con- 

 struction, much larger than the embryo within, which, by the 

 help of a glass, appears like a dark dot in the middle of the 

 single cellular integument. Perfect fructification seems to have 

 taken place in all the extraordinary number of small seeds in a 

 seed-vessel, though their coming to maturity seems to be pre- 

 vented by their being so numerous. In the few cases in which 

 germination has been observed, the embryo gradually swells and 

 forms itself into a tuber before it makes roots; and, as it appears 

 that all seeds of the Orchidaceae undergo this metamorphosis, it 

 may account for their being so difficult to germinate, as other- 

 wise, from the nature of their testa, it is probable they would 

 very soon come up. Finally, among plants of a lower organis- 

 ation, there are beautiful analogies between seed and seed- 

 grains. Thus, Mnium androgynum L. scarcely ever perfects its 

 fruit; but, instead of it, there apjiear on the point of the fruit- 

 stalk granules or seed-buds. The whorl of leaves which forms 

 the capsule decays, and on the fruit axis, instead of real seeds, a 

 number of small stalked seed-grains are found formed, like little 

 beads. This formation will be understood from the above de- 



