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easier and more satisfactory to work with than several among the 

 preceding monographs. 



It opens up afresh the whole question of the "form ' which 

 should be given a monograph on this scale. Now, the form is not of 

 much importance to the next monographer; he has to get the whole 

 of it and all the plants represented by it into his head somehow; and 

 long before he has done this he has got quite used to the arrange- 

 ment (or want of arrangement) of his predecessor, and values his 

 predecessor's work at its sterling worth. But a work of this kind 

 is not meant only for the next monographer, perhaps fifty years 

 hence ; the justification of its being printed is that it should be a 

 helpful book in the herbarium to every man who has a few (or only 

 one) species of Guttiferse to name or deal with— against time (as 

 nearly all work has to be done now). This man cannot spend a 

 preliminary day or two in mastering the language, the arrange- 

 ment, or the system of the monograph ; the form is everything to 

 be information of the book is put into the ordinary form, 

 and if all the citations are complete, all the books " exhausted," so 

 that he can get at all he wants speedily, this makes the book 

 valuable to him. If the book leaves him in doubt whether a 

 species is MS. or published in some obscure place, he may be 

 occupied some time in trying to satisfy himself that it never has 

 been published; if the monograph cites " Willd." but does not cite 

 also " Kunth," he may spend some time and finally write a letter to 

 North America, to endeavour to discover whether the plant of Willd. 

 was the same as the plant of Kunth. He therefore says, all this 

 work should have been done for me by the monographer when he 

 had all the plants at his fingers' ends and all the literature 

 collected. It would have been a general saving of time for this 

 work to have been done then. 



We come at last to the question of the systematic value of the 

 anatomy of the leaf, which occupies so large a portion of Vesque's 

 Guttifera). There has been a not uncommon opinion that here 

 also the question of time comes in,— that even if the anatomic 

 details are constant for each genus or each species,— that they are 

 of small use because there is not time, in ordinary herbarium work, 

 to go into " histologic characters." This idea is to a great extent 

 erroneous ; the time occupied in making a thin section of a leaf 

 winch will show the characters described by M. Vesque (including 

 that of taking off a thin slice to show the stomata), is really not 

 greater than that required to determine the position of the ovules 

 in a small ovary ; the manual skill required is less, and the chance 

 of error of observation is (in my opinion) less. The chance of error 

 is not, I think, sufficiently considered by botanists in their estimation 

 of methods; it is a favourite plan with botanists to count the 

 number of style-branches in herbarium examples with a pocket 

 lens; I find the percentage of errors in fact thus introduced so 

 high as to vitiate whole systems of classification. 



It must also be recollected that, in many important cases, we 

 have always valued highly and used, in the first steps of investiga- 

 tion, the anatomic method. Does not every tyro look for the trans- 



