226 SUMMARY OF CURRENT RESEARCHES RELATING TO 



storing tissue ; in others the leaves are succulent, and there are no 

 hydathodes. In this group the cuticle is strongly thickened, and the 

 stomates are placed in depressions. All the species have a xerophilous 

 structure. 



Stem-structure in Schizaeaceae, Gleicheniaceae, and Hymenophyl- 

 laceae.* — Mr. L. A. Boodle calls attention to the fact that there is a wide 

 diversity in the types of stem-structure shown hy the different members 

 of the Sehizaaaceae. The four genera of which the order is composed — 

 Lygodium, Aneimia, Mohria, and Schizsea — agree, however, in having a 

 stem-protoxylem which is not well-marked, as it consists of elements 

 which are not annular or spiral, and are usually not specially small. 

 The Gleicheniaceae and Hymenophyllaceaa include forms with a solid 

 central mass of xylem ; the protoxylem is well-marked, and is composed 

 of annular and spiral elements in both orders. The author regards the 

 solid stele as the primitive form, from which the Aneimia type has been 

 derived. 



Algae. 



Tendrils of Algae.t — Herr M. Nordhausen describes the structures 

 in certain alga? which have the appearance and function of tendrils. 

 They are confined to the Florideae, and are especially abundant in the 

 genus Hypnea, but occur in several different families. Three species 

 are described in detail as typical, viz. Hypnea musciformis, Spyridia 

 aculeata, and Nitophyllum uncinatum. The hooked branch differs in its 

 branching from the rest of the thallns, in accordance with the function 

 of the hook, which is the same as that of a tendril, viz. to enable the 

 plant to cling hold of other stronger plants, and thus to support itself 

 in the water. Hook-like structures occur on the root as well as on the 

 frond. 



Notheia anomala.J — Miss Ethel S. Barton has studied the structure 

 and development of this seaweed, the only known parasite belonging 

 to the Fucaceas, found on Hormosira and Xiphophora. The growing 

 point consists of three apical cells, and forms the topmost point of the 

 thallus, not lying at the base of a depression. The development of the 

 cryptostomates into conceptacles is described in detail. The antherids 

 and oogones are found in the same conceptacle. The antherids are not 

 formed on branched hairs, as is usually the case in the Fucacea?, but 

 spring directly from the wall of the conceptacle. Each ooyone contains 

 eight oospheres. It is a true parasite, rhizoids given oil' from the base 

 of the pseudo-cryptostomate penetrating between the cells of the host- 

 plant. 



Polymorphism in the Phgeosporeae.§ — Herr F. Kuckuck gives several 

 other illustrations of heteromorphy in the PhasosporeaB similar to that 

 of Cutleria and Aglaozonia. 



Pogotrichum jiJiforme is parasitic on Ziaminaria saccharina near 

 Heligoland, and occurs in January, in a branched monosiphonous pros- 

 trate form, withplurilocular sporanges, which might well betaken for an 



* Ann. of Bot., xiii. (1899) pp. 624-5. 



+ Pringsheim's JahrD. f. wiss. Bot, xxxiv. (1899) pp. 236-78 (1 pi.). 

 J Journ. Linn. Soc. (Bot.). xxxiv. (1S99) pp. 417-25 (3 pis.). Cf. this Journal, 

 1893, p. 762. § Festfechr. f. Schttendener, 1899, pp. 357-85 (1 pi. and 12 tigs.). 



