700 SUMMARY OF CURRENT RESEARCHES RELATING TO 



The differentiation in the development of the megasporangcs and 

 microsporanges is described in detail. They are indistinguishable until 

 they have attained a size of 15,000 to 25,000 cells. The number of 

 microspores in a microsporange is 150,000 to 300,000; of megaspores 

 in a megasporange 150 to 300. In both kinds of sporange the tapete is 

 organised out of the layers of sterile cells adjacent to the mother-cells of 

 tlie spores. The first leaves of a season are megasporophylls, and these 

 are succeeded by microsporophylls ; occasionally a sporange contains 

 both kinds of spore. 



Algae. 



Assimilation, Transformation of Starch, and Respiration in the 

 Floridese.* — According to Herr E. Kolkwitz, the starch of the Florideae- 

 does not differ essentially from that of the higher plauts. It is used 

 up in the same way after being stored up. Whether there are also 

 reserves of albuminoids is doubtful. There are but few Floridese which 

 contain no starch. The red pigment appears to influence the accumula- 

 tion of starch, assimilation, growth, and respiration. Respiration is 

 but very feeble in the FlorideaB ; hence the absence of intercellular 

 spaces. 



Movements in Bornetia secundiflora.j — 'Continuing his observa- 

 tions on this singular phenomenon, Sig. A. Preda states that it com- 

 mences in the cylindrical cells of the thallus,' the apical portion of 

 which swells up enormously under the influence of fresh or distilled 

 water, while the basal portion retains nearly its normal diameter, thus 

 giving a somewhat pear-shaped form to the cell. When the cell fiually 

 bursts, the cytoplasm contracts, detaches itself from the longitudinal 

 walls, and forms an axile band still attached to the two septa, or to the 

 basal septum if the cell be a terminal one. The chromatophores gradu- 

 ally lose their red pigment, which diffuses itself through the water. 

 The thallus of Bornetia appears to possess the power of gradually 

 adapting itself to a less saline or less aerated medium than that which 

 it normally inhabits. 



Structure and Reproduction of Compsopogon.; — [Mr. B. Thaxter 

 has examined a species of this rare and peculiar tropical alga from 

 Florida, distinguished by its bluish or violet-green colour, and by the 

 filaments being composed of an axial row of very large cells surrounded 

 by one or more layers of corticating cells — the sole representative of 

 the family Compsopogonaceae. The cells of the filaments show an active 

 circulation of the protoplasm. Multiplication takes place by aplano- 

 spores, which vary greatly in size, and may possibly be of two kinds, 

 mega- and micro-aplanospores ; the former are produced singly in the 

 sporange ; both kinds are globular, and destitute of cilia. No sexual 

 organs were discovered ; but it is possible the micro-aplanospores may 

 be antherozoids. In accordance with our present state of knowledge, 

 the author thinks the safest place for Compsopogon is near the Ban- 

 giaccfe. 



* Wissensch. MeeresunttK. kerausgegeben in Kiel, iv., Heft 1, pp. 31-02. See 

 Hedwigia, xxxix. (1900) Beibl., p. 88. 



t Nuov. Giorn. Bot. Ital., vii. (1900) pp. 209-14 (I pi.). Cf. this Journal, ante, 

 p. 359. % Bot. Gazette, xxix. (1900) pp. 259-66 (1 pi.). 



