124 SUMMARY OF CURRENT RESEARCHES RELATING TO 



for which he proiioses the name Dermatopliyton radians, is uncertain. The 

 mode of growth resembles that of Coleochsete ; but it forms a continuous 

 parenchyma with thick cell-walls, resulting from repeated horizontal 

 divisions of all the cells cut off from the marginal cells and from inter- 

 calary divisions. The lowest cell of each of these erect rows elongates 

 below to a wedge-shaped form, and penetrates into the horny tissue of the 

 shell, as tlie marginal cells of the whole plant do. By this means the shell 

 is broken up into lamellfe. The mode of reproduction is not described. 



Algae epiphytic on Nymphseacese.* — Sigg. G. B. de Toni and D. Levi 

 Lave examined the algas found attached to the leaves of Ni/mphsea alba and 

 Nuphar lutea in the botanic garden at Padua. They find 39 species in all, 

 of which 19 are now to the Venetian flora. They comprise 24 species of 

 diatoms, 2 Chroococcaccfe, 2 Oscillariacese, 1 Eivulariacea, 1 Coleochte- 

 tacea, 2 QEdogoniacese, 1 Volvocinea, 5 Protococcacese, and 1 Conjugata. 



Action of Algae upon Water.t— According to M. E. Breal, the micro- 

 scopic algse in fresh water decompose bicarbonate of lime dissolved in the 

 water, and thus give rise to a calcareous deposit. Being able to live in 

 neutral or slightly alkaline liquids, they may, by the oxygen which they 

 disengage, serve to oppose or even arrest putrefaction. They rapidly 

 remove nitrates and ammonia from water, since these two substances supply 

 the nitrogen necessary to their growth ; in the dark, however, liquids 

 charged with these algae evolve ammonia. 



Prolification of Cauleipa.l — Di". J. H. Wakker has investigated this 

 phenomenon in cultures of C. proJifera from the Bay of Naples, and finds 

 that it may take place abundantly in each of the parts of the very large 

 single cell which represent physiologically the rhizome, the roots, and the 

 foliage of higher plants. In the "leaf" he has found as many as eleven 

 successive prolifications in connection with one another. Dr. Wakker 

 suggests that the production by Caulerpa of zoospores, which has very 

 seldom been observed, is extremely rare, and that the chief mode of repro- 

 duction to which is due its very extensive growth, is this prolification. 

 The author's researches are opposed to the conclusion of Sachs that the 

 roots of plants grow only at their base, and buds at their apex, and that the 

 direction is determined by the force of gravity. 



Hildebrandtia and Dichosporangiuni.§ — Herr E. Wollny has repeated 

 his observations on the antheridia of Hildebrandtia, but suggests that when 

 the mode of reproduction is fully known, it will be found that the plant 

 described by him really belongs to Peyssonellia. 



He also describes a new species of Ectocarpaceae, DicJiosporangium 

 Chordariae, with both unilocular and niultilocular zoosporangia. 



Hauck and Richter's Phycotheca universalis. — The first part is now 

 issued of this very useful and valuable publication, consisting of dried 

 specimens of fifty species of fresh-water and marine algae, belonging to a 

 great number of different orders. 



Terrestrial species of Ulotlirix.|| — M. E. de Wildeman describes in 

 detail the two terrestrial species of Ulothrix (Hormidium Ktz.), U. radirans 

 and U. parietina, especially the " radicles " characteristic of the former 



* Malpighia, i. (1886) pp. 60-7. 



t Ann. Ajp-ononi., xii. (1886) pp. 317-32. Cf. Journ. Chem. Soc. Lond — Abstr., 1. 

 (188G) p. 1060. 



X Versl. en Meckel. K. Akad. Welen. Amsterdam, 1886, pp. 2.51-64 (1 pi.). 

 § Hedwigia, xxv. (1886) pp. 125-32 (3 pis.). See this Journal, 1886, p. 659. 

 II Bull. Soc. K. Bot. Belg., xxv. (1886) pp. 7-18 (1 pi.). 



