330 A.Gray — Flora of North America. 



botanists, and the Torrey herbarium goes back one generation 

 farther. Still the number of American specimens annually 

 coming to it is greater than in most former years. Apart from 

 the mere selection and care of these, consider how in other 

 ways it affects the rate of progress of the Flora, The incoming 

 of additional specimens may at a glance settle doubts as to the 

 validity of a, species; but new specimens are as apt to raise 

 questions as to settle them ; more commonly they raise the 

 question as to the limitation and right definition of "the species 

 concerned, not rarely, also, that of their validity. When one 

 has only single specimens of related species, the case may seem 

 clear and the definition easy. The acquisition of a few more, 

 from a different region or other conditions, almost always calls 

 for some re-consideration, not rarely for re-construction. Peo- 

 ple generally suppose that species, and even genera, are like 

 coin from the mint, or bank notes from the printing press, each 

 with its fixed marks and signature, which he that runs may 

 read, or the practised eye infallibly determine. But in tact 

 fcs- -judgments of variable value, and often 

 very fallible judgments, as we botanists well know. And 

 genera are more obviously judgments, and more and more 

 liable to be affected by new discoveries. Judgments formed 

 to-day — perhaps with bill confidence, perhaps with misgiving 

 — may to-morrow, with the discovery of new materials or the 

 detection of some before unobserved point of structure, have to 

 be weighed and decided anew. You see how all this bears 

 upon the question of time and labor in the preparation of the 

 Flora of a great country. If even irvold Europe the work has 

 to be done over and over, how much more so in America, 

 where new plants are almost daily coming to hand, ft is true 

 that these fall into their ranks, 'or are adjustable into their 

 proper or probable places, but not without pains-taking and 



Of our Flora, it may indeed be said, that " If 'twere done 

 when 'twere done, then 'twere well it were done quickly." 

 But I may have made it clear that, in the actual state of the 

 case, it is likely to be done slowly. At least you will under- 

 stand why thus far it has been done slowly. As to the future, 

 if it depended wholly upon me, the completion would obvi- 

 ously be hopeless. 1 need not say that our dependence, for the 

 actual elaboration, must largely be upon associates, upon the 

 few who have the training and the vast patience, and the access 

 to herbaria and libraries, requisite for this kind of work, but 

 above all upon my associate in the herbarium at Cambridge, to 

 whom, being present with us, I will not further allude. 



Of course we rely, very much indeed, upon the continued 

 cooperation of all the cultivators of botany in the country ; and 



