428 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the formation of cork is usually retarded as long as possible. The 

 periderm most often takes the form of longitudinal strips, formed in such 

 a way as to disturb the assimilating tissue as little as possible. These 

 strips often remain for some years ; finally they coalesce, and then for 

 the first time form an unbroken periderm, such as is developed during 

 the first year in nearly all woody plants. 



Anatomy of Menispermacese.* — M. E. Blottiero describes the anato- 

 mical structure of typical species belonging to each tribe of this order. 

 Its affinities ho believes to bo with the Lardizabalea3. He proposes to 

 classify the genera under five suborders, characterized by the nature of the 

 fruit, whether drupaceous or baccate, by the number of ovules, whether 

 one or many, and by the presence or absence of endosperm and of a 

 laticiferous system. 



Anatomy of the Stem of OrehidesB-t— Herr M. Mobius points out 

 that in both their structure and arrangement the fibrovascular bundles in 

 the stem of a large number of native (German) Orchidea) present a singu- 

 lar approach to those of Dicotyledons. 1'he bundles are arranged in a 

 single ring, in the uppermost jiortion of the stem, and show at least 

 traces of an active cambium. The detailed structure is described in a 

 number of different species, and it is shown that the chief differences are 

 correlated with differences in the structm-e of the labellum and in other 

 floral characters, the Ophrydeae and the Neottiete presenting two distinct 

 types. 



Structure and Geographical Distribution of Plumb agineae.j — M. P. 

 Maury takes as his type of this order the genus Plumbago. The primary 

 structure of the internal part of the root is as follows :— Inside the 

 endoderm one or more layers of cells constitute the rhizogenous layer, 

 enveloping the central cylinder, formed of four woody bundles in the shaj)o 

 of a cross, alternating with which are four liber-bundles. In the young 

 stem the author recognizes (1) the epidermis, (2) a cortical zone of eight or 

 ten layers of cells, (3) the endoderm, (4) the zone of liber, (5) the centi*al 

 cylinder formed of eight fibrovascular bundles, separated by large medullary 

 rays, and leaving a large portion of pith in the centre. On the stems and 

 leaves of Plumbagineas are frequently numerous small masses of carbonate 

 of lime, often united in a sort of crust. Their formation has been exj)lained 

 by Licopoli. The mother-cell divides simply into four, each of these cells 

 is secretory, their product collects in the intercellular space, and is 

 excreted by the tension of the cells which remain always united on their 

 lower surface. The author states that the inflorescence of all the Plumba- 

 gineae is constructed on the same plan. It is a mixed inflorescence 

 formed of dichotomous cymes, developed singly by abortion, and grouped 

 in a paniculate or capitulate manner. 



M. Maury admits the axile nature of the ovule of Plumbaginete. With 

 regard to the affinities of this natural order, its nearest relationships are 

 with Primulacca) and Polygonacefe. 



The remaining portion of the memoir is devoted to the geographical 

 relations. Of the 267 species of Plumbagineas, 52 are European, 123 

 Asiatic, 39 African, 11 American, and 2 Oceanic; the remaining 4.0 are 

 common to two or more continents. 



* Blottierc, R., 'Etude anatomiqiie de la famillo des Mcnispermees,' 71 pp. and 

 2 pis., Paris, 1S86. 



t Bii: Deutsch. Bot. Gesell , iv. (18SG) pp. 284-92 (1 pi.). 

 X Ann. Sci. Nat. (Bot.), iv. (188G) pp. l-13i (6 pis.). 



