179 



In the case of Cynometra warhiirgii Harms, a carbon rubbing of 

 two or three leaves of the type enabled me at once to determine 

 the identity of the species when it finally appeared in our Philip- 

 pine collections, although the second collection of the species 

 was sterile, that is, without flowers and without fruits. While 

 at Berlin the Director of the Museum Kralovstovi Ceskeho at 

 Prague kindly loaned me a number of types of Philippine plants 

 collected by Haenke, among them four types of Piper described 

 by Opiz. Of these types I made carbon impressions of the leaves. 

 These carbon rubbings were later submitted to M. C. DeCan- 

 dolle with the Philippine specimens of Piper, whereupon he was 

 able definitely to place all of them, although in his monograph 

 of the Piperaceae* all were placed under the heading "Species 

 non satis notae." Two species described by Opiz, of which I 

 did not see the types, Piper haenkeanum and Piper rufinerve, 

 and hence secured no leaf impressions, still remain unrecognizable 

 because of their imperfect original descriptions. f 

 , Carbon rubbings or impressions of leaves not infrequently 

 present details of the venation better than do some photographs, 

 and have the distinct advantage of always showing the leaf the 

 exact size of the original. It is believed that in many cases 

 carbon leaf prints would be a valuable adjunct to actual photo- 

 graphs of types. 



The leaf prints can be mounted on herbarium sheets, pro- 

 tected against undue rubbing or smudging by a protective flap 

 of some thin smooth paper, such as onion skin paper, and are 

 thus immediately available for purposes of direct comparison. 

 The original description, and other data, can be copied on the 

 sheet with the leaf impression. From a simple examination of a 

 carbon rubbing of a typical leaf of a type, together with a study 

 of the original description and the examination of additional 

 material from the same general region from which the type came, 

 species that have long been obscure, unknown, or entirely over- 

 looked, can usually be recognized. This applies even in such 



* Prodromus i6': 2358^-471. 1869. 



t DeCandolle, C. A Revision of Philippine Piperaceae. Philip. Journ. Sci. 

 5: Bot. 405-463. 1910. 



