526 ORGANOLOGY. 



municability ; and it would cease to be science, or capable of develop- 

 ment, if it remained confined to individual men, or perished with them. 

 We must, then, in this case, devise a plan by which we may make use of 

 the previous consciousness to assist in the application of the law of 

 specification. 



The most acute definition of the idea of species is the following : " To 

 one species belong all individuals which exhibit, independent of time 

 and place, and under the same circumstances, precisely the same cha- 

 racters." It is, however, in only a few instances that we are able to 

 apply this principle for the definition of a species, least of all in those or- 

 ganisms in which the conditions of existence are so multiplied and en- 

 tangled, that we can seldom entirely comprehend all, and therefore never 

 establish a perfect identity of circumstances. 



We must here hold fast the importance of the history of development 

 as the principle of Botany ; only in this can we hope to find a notion of 

 the species that can, in the course of time, afford a group of constant 

 and similar characters; but this constancy must be observed in the 

 plant generally, and not in the perishing individual, and must continue 

 through many generations. Nothing can be held to be a species which 

 does not originate in an individual of the same kind ; and, therefore, 

 nothing that originates in spontaneous generation can be held as a species 

 of plant, although it may otherwise, as a natural body, find a specific 

 distinction. 



The determination whether a plant is a species or not. will long 

 remain the most difficult problem in Botany. If we had the entire 

 knowledge of plants, and the laws of their morphological development, 

 at our command, we should then be able to make our distinctions upon 

 fundamental differences which necessarily flow from the idea of the 

 plant beginning from above and passing down, till, out of those known 

 laws which lie at the limits of the comprehension of the individual, we 

 arrive at the idea of the species. The solution of this question will yet 

 long remain an impossibility. Every other definition of the species pre- 

 sents endless difficulties, which proceed from the nature of the plant. 

 The independence of cell life, and the principle which lies at the basis 

 of reproduction, present especial difficulties. As cell life is independent 

 of the morphological combinations under which it appears ; so can a form 

 which is evidently only in the early stage of its development, endure for 

 a long time, because the conditions of its entire development fail, and 

 at last become very much complicated : hence this form may be found 

 in a large number of individual cases as the entirely developed plant. 

 Further, as the foundation of reproduction depends upon the capabilities 

 of such cells to develope themselves according to the same morpho-- 

 logical laws as belong to the whole plant, so may we have, in an earlier 

 stage of development, an individual cell from the mass, which, although 

 it may have the power, yet needs the circumstances to develope a perfect 

 plant, and presents a less complete form ; so that whole families of plants 

 that for a time appear essential, yet consist of unessential forms. Sup- 

 pose that caterpillars and maggots had the power of propagating them- 

 selves, and their power of developing themselves into perfect insects 

 existed under conditiops very rarely arising, would not these be cited, 

 at least for a time, as a peculiar family in Zoology ? Hence we may 

 conclude, that the growth of forms is the governing principle in the 

 vegetable world, and the invariable (essential) characters by which we 

 define classes are necessarily of a morphological nature. But the em- 



