100 Selections from the Correspondence of 



and to judge which of the botanists have pursued the method 

 most conforming to the natural in their system ; for I find that 

 they all sometimes differ widely in this respect. For example, 

 Linnaeus ranks under the genus of Convallaria and under Loni- 

 cera, plants which all other botanists referred to several different 

 genera : indeed, I think the parts of fructification in many of 

 them may be sufficiently distinguished. On the other hand, it 

 is very difficult for me to distinguish the genera of many of the 

 class of Hexandria which he makes distinct. Since there is no 

 manner of concord as to this grand point in botany among the 

 ablest botanists, I may be allowed to suspect that no sufficient 

 criterion has yet been discovered.* 



I must therefore conclude, that however unsystematical and 

 artless Mr. Ray's taking in the tota fades of plants into his dis- 

 tinction of the genera may be thought, we cannot entirely throw 

 it aside, till some better criterion be found than has hitherto been 

 given by botanists. For, so far as I can judge from the charac- 

 ters of plants given by others, and what little observation I have 

 made, the parts of fructification alone, that is, the outward shape 

 and form, number of cells, &c. is not sufficient in every case to 

 distinguish the genera. Neither are the general shape and form 

 of the leaves, stalks, and roots, or their proportion to each other, 

 sufficient to distinguish the species, but that sometimes some 

 other circumstances are to be considered, as particularly that of 

 the time in which they acquire maturity. 



But notwithstanding these objections I make to Dr. Linnasus's 

 system, they no way lessen the esteem and value I have for his 

 works ; for I am more obliged to him than to any botanist I have 

 seen. It is wonderful with what exactness he has observed such 

 a vast variety of plants ; and it is as wonderful to me that he has 

 made so few mistakes in this great performance. What objec- 

 tions I make to his system will almost equally affect all systems. 

 We have not as yet sufficient knowledge to adapt our systems 



* Dr. Colden then proposes the faculty of hybridization as a test of this point, 

 and considers those species which hybridize as belonging to the same genus, and 

 those that cannot be made to hybridize to belong to different genera, and proceeds 

 to defend this view by various illustrations drawn both from the vegetable and 

 animal kingdoms. In his subsequent letter to Linnaeus, (published in full by 

 Smith in his Correspondence, I. c. Vol. II, p. 452,) he considers the same subject 

 in a similar manner. It is hardly necessary to state, that he seems to confound 

 proper varieties with hybrids. — A. G. 



