672 SUMMARY OF CURRENT RESEARCHES RELATING TO 



of which is abundantly provided with stomata, and which apparently 

 serves for purposes of assimilation. Similar structures were found in 

 a previously undescribed species, B. Odoardi, from Borneo. 



Idioblasts containing Albuminoids in some Cruciferse.* — Herr 

 E. Heinricher describes the structure of peculiar cells found beneath 

 the epidermis in the leaves of Moricandia arvensis, not readily dis- 

 tinguishable in the living state from the ordinary assimilating cells, 

 but easily differentiated on treatment with alcohol, when their con- 

 tents are seen to be chiefly, if not exclusively, of an albuminoid 

 character ; they contain neither sugar, starch, nor tannin. In Mori- 

 candia these peculiar cells occur also in the floral organs with the 

 exception of the petals and stamens ; and the author has detected 

 them also in four other species belonging to the tribe Brassiceee of 

 Cruciferse, viz. Diplotaxis tenuifolia, Sinajpis alba and nigra, and 

 Brassica Bapa, where they are found within the assimilating paren- 

 chyma of the leaf, and in the deeper layers of the cortex of the stem 

 and root ; in Diplotaxis tenuifolia even in the pith. 



These cells are certainly not excretion-receptacles, and it is 

 doubtful whether they serve physiologically for the formation or for 

 the storing-up of albuminoids. Morphologically they appear to be 

 most closely related to laticiferous tubes, and are possibly derived 

 from these organs by degradation, thus indicating a phylogenetic 

 af&nity with the allied order of Papaveracese. 



Annular and Spiral Cells of Cactacese.f — M. P. van Tieghem 

 describes the structure and arrangement of these cells, the latter of 

 which may be arranged under three types, all found in different 

 species of the genus Opuntia. In 0. flavicans the stem possesses four 

 fibrovascular bundles separated by large rays, and surrounding a 

 small pith. In these rays and pith the spiral and annular cells are 

 found in large numbers, but not in the bundles themselves. After 

 the formation of the secondary tissues the four fibrovascular bundles 

 are very narrow, but strongly elongated radially, and are separated 

 by four large fan-like secondary rays, which are composed exclusively 

 of spiral and annular vessels, the secondary wood being again entirely 

 destitute of them. The same is the case in 0. flavicans and cylindrica. 

 In 0. tunicata, on the contrary, these cells are localized in the 

 primary and secondary wood, and are wanting in the pith and rays. 

 The same mode of distribution occurs in the genera Mamillaria, 

 Echinocactus, and Melocactus. 0. Salmiana, puhescens, and some 

 other species display a combination of these two arrangements, the 

 spiral and annular cells forming a more or less thick continuous 

 sheath enclosing the wood, and they are also found in the primary and 

 secondary wood. Finally, in O. Ficus-indica, hrasiliensis, and in 

 most species with flattened stem, these elements are altogether 

 wanting. 



As far as their structure is concerned, they are living cells, with 

 perfectly closed cell-wall, protoplasmic body, and nucleus. They 

 constitute in fact a remarkable kind of parenchyma. 



* Ber. Deutsch. Bot. Gesell, ii. (1885) pp. 463-6 (1 pi.). 

 t Bull. Soc. Bot. France, xxxii. (1885) pp. 103-5. 



