Botany. 495 



composition. The portion of the subject taken by the author is 

 on the latter side and, as treated by him, it is a field that has not 

 been occupied before. Some of the topics discussed are the 

 physical laws of crystallization, the origin and growth of crys- 

 tals, the formation of artificial crystals, and the relation between 

 form and composition including isomorphism, physical isomerism, 

 and isogonism. 



10. Composition of uraninite. — In the note on this subject on 

 p. 329 of this volume, line 17 from beginning, N0 2 is a misprint 

 for U0 3 . 



III. Botany. 



1. What is a Phyllodium ? — An examination of two plants of 

 the Brazilian species, Oxalis bupleurifolia, grown from cuttings, 

 has led the writer to review the literature of the subject of phyl- 

 lodia, chiefly with reference to one point. The smaller of the 

 plants in question has flattened petioles without any distinct trace 

 of leaflets at the end. The other has petioles flattened in the 

 same way, and more than half of these have small leaflets, vary- 

 ing in number from one to three. But all of these flattened peti- 

 oles in both cases have a distinct upper and lower surface, thus 

 presenting the aspect of ordinary leaves, instead of having an 

 upper and a lower edge. They stand in the same plane as the 

 leaflets. 



The following definition of the term phyllodium is taken from 



Gray's Text-book, vol. i, p. 110 : "A petiole-blade is 



named a Phyllodium. Occurring only in Exogens, phyllodia are 

 generally distinguished from true blades by the parallel venation, 

 and* always by their normally vertical dilatation; that is, they, 

 without a twist, present their edges instead of their faces to the 

 earth and sky." Among the examples cited, are the Acacias of 

 Australia, and " several South American species of oxalis." 



It will be noticed that in the definition, verticality is not quali- 

 fied. In this respect the definition follows the ordinary usage, 

 based largely upon the authority of DeCandolle, Organographie 

 vegetale, Paris, 1827, p. 282. " Ceux-ci sont planes, coriaces, 

 fermes, toujours entier sur les bords, munis de nervures longitudi- 

 nales, qui sont les traces des fibres dont le petiole est compose, et 

 habituellement places sur la tige dans un sens contraire aux vraies 

 feuilles, c'est-a-dire que leur plan est a-peu-pres vertical, au-lieu 

 d'etre horizontal, ou en d'autre termes, que leurs surface sont later- 

 ales, au-lieu d'etre l'une superieure, l'autre inferieure. 



II est des especes qui, pendant la duree enliere de leur vie, por- 

 tent melanges des petioles charges de folioles urdinaires, et ordi- 

 naires, et des petioles transformed en phyllodium. Telles sont les 

 Acacia heterophylla, sophorae, etc. Quelques-uns portent sur 

 leur bord superieur une ou deux glandes qui indiquent la place oil 

 le ramifications chargees de folioles doivent prendre naissance. 



* The italics in these citations are not in the original.— G. l. g. 



