98 



justifiable. Electrotype plates for the illustrations have been sub- 

 stituted for the original stones and copper plates, which has per- 

 mitted their printing upon thinner paper and the placing of the 

 explanations opposite the plates to which they refer. A thin 

 but firni paper has been used for the whole volume, and the 

 result as respects bulk is that, the book is both thinner and 

 lighter than even the last edition. 



In the elaboration of the matter that has been admitted it 

 was, of course, impossible to please everyone. What appears a 

 fault to one will be an excellence in the judgment of another. 

 In the portions that had not recently been revised by Dr. Gray 

 himself the work is necessarily unequal, inasmuch as some or- 

 ders have been subject to more or less thorough and trustworthy 

 revisions by various botanists, while others have had no especial 

 attention given to them for years. It was necessary to make the 

 best of what was at hand, and this has been done as far as the 

 limited time permitted, every known available source of informa- 

 tion up to the very latest date being made use of, and no little 

 original work intercalated where it seemed most needed. All the 



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conclusions and determinations that have been published have not, 

 however, been adopted, for what seemed In each case to be good 

 reasons. A case in point is one referred to by Prof Porter in 

 regard to Gcutimia alba, Muhl,, a name w^hich he considers that 

 he has '* clearly proved untenable." But a careful consideration 

 of the whole question, including a reference to Muhlenberg's 

 manuscripts, convinced me that Dr, Gray's conclusion was prob- 

 ably the more correct one. 



The undue multiplication of varieties has not been favored. 

 Everyone must understand that species vary, some more and 

 some less, but all to some extent. The attempt to define and 

 name these variations is in the great majority of cases of little 

 profit, especially in a manual like the present. 



The determination of the range of species was often a difficult 

 and unsatisfactory matter. Numerous local catalogues, more or less 

 reliable, the Gazette, THE BULLETIN, the Gray Herbarium, were 

 at hand and were consulted whenever there seemed occasion for 

 it. That there should be not a few errors of various kinds is 

 not strange, and I am not at all surprised that the keen scent of 



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