ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 61 



The water contained in them is not merely rain-water, but condensed 

 atmospheric moisture, which makes them more independent than terres- 

 trial types. Also, the contents of the reservoirs do not decompose, but 

 are chemically transformed into a light-brown cellulose substance re- 

 sembling cardboard. The whole of intertropical America, through 

 which these plants are spread, offers a unique habitat to various animals, 

 ranging from Batrachians to Protista. This fauna is very constant, and 

 can only be accounted for by assuming that the eggs or larvae are trans- 

 mitted from one individual to another, e.g. by actual contact, by parts 

 of old plants falling on seedlings beneath them, etc. 



Epidermis and Respiratory-apparatus of the Bromeliaceae.* — K. 



Linebauer has studied a large number of Bromeliaee», with special 

 reference to the physiological anatomy of the epidermis and the methods 

 of respiration. The author finds that, not only have they a characteristic 

 abnormal thickening of the epidermal membrane, but that the lateral 

 membranes, or at least their middle lamellfe, have an irregular structure 

 which may be more or less hidden by secondary layers of thickening. 

 The epidermal cells are in contact with the hypodermis, and there is a 

 continuity between these two tissues. Usually, every epidermal cell 

 contains silica. All tlie upper tissues are differentiated according to 

 function ; the hypodermis forms a mechanical protection ; the storage 

 of water is undertaken by the water-tissue ; the epidermis, as the bearer 

 of the cuticle, really acts only as an organ of protection against excessive 

 loss of water. The stomata are characterized by peculiar guard-cells, 

 the absence of a posterior air-chamber, and the possession of one or more 

 pairs of auxiliary cells which control the movement of the stomata, and 

 protect the water-tissue. The narrowing or closing of the stomata may 

 be brought aljout in different ways ; they may be wholly or partially 

 closed by the auxiliary cells, or growth of the hypodermal cells may 

 partially close or stiffen the air-passage, or the latter may be entirely 

 stopped up by membranous stoppers formed by the trichomes. The 

 transpiration-tissue arises by the adaptation of a system of intercellular 

 canals (surrounded and traversed l)y chlorophyll-bearing parenchyma), 

 which run parallel with the vascular bundles throughout the length of 

 the leaf without uniting with one another. From these branch out 

 narrower canals, approximately perpendicular to the surface of the leaf, 

 which pass out through the stomata. This form of respiratory apparatus 

 allows of open stomata, with an extensive reduction of transpiration 

 without interfering with the absorption of CO^. 



Reproductive. 



Seed-structures of American Fossil Cycads.t— G. R. Wielaud 

 publishes the results of his work upon fossil Cycads. The present paper 

 deals with seed-structures, especially as seen in the Cycadeoidean trunk, 

 discovered near the Black Hills, also in Bennettites Gibsonianus and B. 

 Morierei. The first specimen is a monocarpic trunk, bearing small-sized, 



* Sb. Akad. Wiss. Wieu, cxx. 4 (1911) pp. 319-318 (3 pis.) 

 t Amer. Jouru. Sci., xxxii. (1911) pp. 138-55 (9 figs.). 



