494 SUMMARY OF CURRENT RESEARCHES RELATING TO 



water very reailily from rain or dew. The course of the rise of water 

 by cai)ill!irv attraction iu such a moss as Ilijlocominm lorcnm can be 

 very well followed under the IMicroscopc by tinging with anilin-bhie. 

 The effect of a carpet of moss on the soil, whether living or dead, 

 is exactly that of a sponge. Especially when growing on steep 

 declivities, it iirevents both the rapid saturation and the rapid drying 

 of the soil. Sphagna, on the other hand, which almost invariably 

 grow iu wet situations, have a precisely opposite effect in holding a 

 very large proportion of the water whicli falls as rain, and promoting 

 rapid transpiration, and thus, in a certain sense, assisting in the 

 drying up of bogs. Sphagna have also the property of absorbing 

 dew, which otlier mosses have not. 



Algee. 



Batrachospermum.* — M. S. Sirodot publishes a complete mono- 

 graph of this family of Floridca^, a group subject to extraordinary dif- 

 ferences of form, according to the influence of the season, the supply 

 of water, the dejitli at which they live, and the degree of illumination. 

 When inhabiting deep springs they present all the phenomena of 

 etiolation. According to the external conditions under whicli they arc 

 developed, the Batrachospermca3 are found in three different modifica- 

 tions, viz. (1) a primordial condition, ov prothnlHum ; (2) a non-sexual 

 condition, or Chantransia ; (3) a sexual condition, or Batrachosjjermum. 



The prothallium, which has been hitherto overlooked by observers, 

 is a kind of crustaceous pellicle covering the surface of the stones on 

 which the plant grows. It is composed of irregular filaments, which 

 are sometimes agglomerated into globular masses. This structure is 

 of great importance, since in the perennial species it is the part which 

 renders the plant able to persist. It is capable of growth and re- 

 production, increasing by the periphery and reproducing itself by 

 sporules. There are, iu fact, several species, e. g. B. sportilans, in 

 which this is the normal mode of reproduction. 



The non-sexual form is composed of broad tufts of filaments, each 

 consisting of a row of cells, ramifying and producing sporules alto- 

 gether analogous to those of the prothallium. Since this form can 

 reproduce itself through a number of generations, it has long been 

 regarded as a distinct genus under the name Chantransia. The fresh- 

 water species of Chantransia live on the most shaded walls of wells, 

 developing chiefly in darkness, while the sexual form, on the other 

 hand, seeks the light. Hence the great difficulty in determining a 

 genetic connection between the two, in which, however, M. Sirudot 

 has succeeded in the case of Chantransia pygmcea, chalyhea, and 

 ramellosa, which are the non-sexual state of different species of 

 Batrachospermum, C. chahjhea representing several species of the 

 latter genus. It is usually the extremity of a stunted foot of 

 Chantransia that is transformed into the sexual form. 



* Sirodot, S., ' Les Batrnchospermes, organisation, fbnotioiis, developpenient, 

 classification,' 300 pp. aud 50 pis. See Bull. Soc. Bot. France, xxxi. (1884) Rev, 

 Bibl., p. 182. 



