78 SUMMARY OF CURRENT RESEARCHES RELATIKG TO 



S. undidata, the leaf-cells are either thin-walled or of even thickness 

 throughout ; in S. irrigua the cells have triangular thickenings. These 

 differences in areolation are hereditary (phjletic). S. paludosa C. M. is 

 here regarded as an extreme and striking swamp- form of the very 

 variable S. undulata, forming perhaps the opposite pole in S. dentata, 

 which is the other extreme of S. undulata^ S. dentata occurring in the 

 Upper Harz mountains, and being regarded as a xeromorphosis of 

 S. undulata. In herbaria the two species distinguished above lie side 

 by side under S. paludosa. Since the name was created for the former 

 of the two, the name of S. paludicola Loeske et C. Miill. is created for 

 the latter. A considerable portion of the northern Martinellia paludosa 

 belongs to S. paludicola. Two conditions help to bring about such 

 parallels : the respective original species must be closely allied (as is 

 the case here), and demand similar conditions. But they must be also 

 very variable and extremely open to influence by the action of water. 

 In the case of Fhilonotis the action of water brings about variation 

 along similar lines to so great an extent that it is sometimes only 

 possible to guess the species, not to determine it with certainty. 



E. S. G. 



Organic Balancing between the Pedicel of the Female Recep- 

 tacle and that of the Sporogonium in Lunularia vulgaris. — 

 P. Lesage {Gomptes Rendus Acad. Sci. Paris, 160, 1915, 679- 

 881). The author obstructed the upward growth of the pedicels of the 

 female receptacles in the species by covering them down with bricks ; 

 and found the pedicels of the sporogonia to become longer than normal. 

 He concludes that in this a compensation may be discerned. A. G. 



Liverworts of Germany, Austria and Switzerland, with Con- 

 sideration of the other European Countries. — K. Mjjller (Raben- 

 horsCs Kryptog amen- flora, Leipzig : E. Kummer, 1916, 6, Lief. 28, 

 849-947). The final part of this monograph. A chapter is devoted 

 to Vertical Distribution of the Liverworts, and another to their Ecology. 

 The dependence of Liverworts on climatic factors (warmth, light, 

 moisture) and on biotic and edaphic factors is discussed. A complete 

 index of families, genera, species, varieties and forms, with all synonyms, 

 completes this work, the preparation for which has taken eleven years. 



E. S. G. 



Thallophyta. 



AlgSB. 



Thalassiophyta and the Subaerial Transmigration. — A. H. Church 

 (Botanical Memoirs, Xo. 3, Oxford University Press, 1919, 95 pp.) An 

 essay on the origin of the Land Flora. The author shows that the 

 latter must Lave ))een derived from the marine alg^e, and indeed from 

 green algie of the highest type of development. Life originated in the 

 sea from the ionized sea-water, yielding unicellular plankton organisms, 

 autotrophic chiefly, but associated with their animal derivatives. To 

 this plankton phase was added after vast ages a benthic phase, when 

 the sea-bottom, slowly elevated to within 100 fathoms from the surface, 



