PHANEROGAMJA : FLOWERS. 337 



Mere, as in all cases where a purely empirical matter is in question, it is 

 infinitely difficult to express in words what a single glance at nature 

 establishes with facility. In point of fact, nature is not indeed so 

 changeable and undefined as might appear at the first glance, for it is our 

 imperfect perception that produces the indeterminateneas in nature. With 

 a complete and profound knowledge of all plants, it would be easy enough, 

 even by a simple sign, without the application of our so uncertain ter- 

 minological instrument, to characterise a given flower intuitively; but 

 for this is required a knowledge of the laws of the structure of forms, of 

 which we have not yet even a presentiment. For the present we must 

 make use of various external aids, but select these in such a manner 

 that tiny may put no compulsion upon nature, but leave the path open 

 to progress in the science. This is only possible by a construction of the 

 definition from actual experience, instead of out of a pretended theory 

 which cannot exist at present ; and, further, by rigid logical classifica- 

 tion of the definitions according to their relative value and dependance 

 upon each other. In the Phanerogamous plant we have, in this way, the 

 axis and leaf as the primarily defined differences; subordinate to this 

 division come the distinctions founded on progressive development and 

 position, therefore on time and space, as the most universal ; then we 

 arrive at the conditions of form, structure, and colour, which are neither to 

 be evolved from the nature of the plant at present, nor have any relation 

 to primary intuitions, therefore can only be empirically comprehended 

 through experience, and must be described with aesthetic clearness. 

 Thus the conception of similarity admits of no general definition in 

 regard to the floral envelopes, but requires actual demonstration; and 

 here we are destitute of the comprehensive knowledge of all cases from 

 which the more general or more restricted importance of the individual 

 characters might with certainty be deduced. Here we must confine 

 ourselves almost entirely to certain groups of plants, within the limits of 

 which an example does not readily lead to error. If we take, for instance, 

 n corolla only symmetrically developed, e. g. a Pea flower, a striking differ- 

 ence among the separate foliar organs cannot be denied; nevertheless 

 they have a certain agreement in colour and texture, which determines us 

 to recognise I hem as similarly developed. How, in most Orchidacea, the 

 lip differs in form and colour from the rest of the perianthial leaves, and 

 yet there is something in its texture in which we perceive it to be similar 

 to them. Colour and texture agree almost perfectly in the calyx and 

 corolla of Ranunculus acris, and yet we distinguish here two dissimilar 

 structures, according to form. Structure, colour, and even almost form, 

 are exceedingly similar in the Moral envelopes of the Amarantacece, and 

 nevertheless we separate, directly we see them, the corolla from the 

 calyx (the inner two of the three so-called bracteoles), &c. From these 

 causes we can, in (leneral Botany, in regard to very many conditions, 

 only indicate the directions in which the study of these has advanced ; 

 and instruction in these tilings must be given by pointing them out in 

 actual specimens ; more special explanations are only possible in Special 

 IJotany, in reference to particular groups of plants, and the attempt to 

 gather them into generalities leads to endless complexity and useless 

 time-wasting repetitions. 



1 have included the epicalyx among the floral envelopes; and, true to 

 the fundamental axiom, that what nature unites man may not divide, I also 



z 



