408 SUMMARY OF CUERENT RESEARCHES RELATING TO 



lacustriue type, from a geographical and ecological point of view ; (2) 

 to see how far the structural peculiarities of the pelagically-f ormed mud 

 strata were dependent on the sediment-building factors, particularly the 

 plankton production, arising from their environment. The material 

 examined consisted mainly of net-plankton, though nannoplankton was 

 also obtained. The methods employed in the collection and examina- 

 tion of the material are described in detail. The results obtained are 

 fully and clearly set forth, but are too wide in scope and too copious in 

 quantity to be adequately reproduced here. E. S. G. 



The Morpholog'y and Physiology of Form-variation (Develop- 

 ment, Reproduction, Fertilization and Heredity) of the Phyto- 

 monadineae (Volvocales). II. On the Continuous, purely Asexual, 

 Cultivation of Eudorina elegans and its Significance for the Pro- 

 blem of Fertilization and Death. — M. Hartmann {Sitz-Ber. kgl. 

 Preiiss. Ale. Wiss., 1917, 7G0-76 ; see also Bot. Centralbl, 191'J, 140, 

 108). The author puts forward the question whether plants, which in 

 a natural condition exhibit sexual and asexual reproduction, can be 

 permanently reproduced without any sort of cell-disturbances other 

 than those involved in the usual cell and nuclear division. Eudorina 

 elegans was chosen for experiment as being convenient for observation 

 with its colony of thirty-two cells. Each of these cells divides five 

 times in the course of a few days (in summer four to seven, in winter 

 twenty days). The author succeeded in rearing 550 individual genera- 

 tions without any sort of interference, and concludes therefore that this 

 experiment, which lasted two and a half years, proves the possibility of 

 permanently cultivating Eudorina asexually. Should this be the case, 

 however, the significance of fertilization is not to be found in rejuve- 

 nescence. Finally, the author discusses death and immortality in many 

 senses. E. S. CI. 



Occurrence of Algae in the Tubes of Utricularia. — E. Lemmerjjann 

 (Vortrag Deidsch. Zool. Gesell. auf 23 Jahresvers. Bremen., 1913, 261 pp., 

 fig. ; see also Bot. Centralbl., 1918, 138, 184). In the tubes of a 

 Utrindarla from Brazil the author found three Protococcacete, twenty- 

 seven Conjugate, two Flagellataa, one Heterokont. Species which 

 develop swarmspores wandered into the tubes while in a state of activity 

 and continued their development in situ. One-celled Desmids behaved 

 in a similar manner. Filament-forming Desmidiaceaj grew in the 

 opening of the tubes and drew other algaj in with them. The phototaxis 

 and the mucilage in the tubes play a part in the phenomenon. One new 

 species, Derepyxis ellipsoidea, and several new varieties are descril)ed. 



E. S. G. 



Contribution to the Paludine Flora of the Environs of Yverdon. — 

 A. Deglon {BuU. 8oc. Vatid. Sci. Xat., 1920, 53, 23-75, 2 figs.). A 

 description of the algal flora of three ponds, situated 1.8 kilom. S.W. of 

 Yverdon, Canton Vaud. The physical features of the ponds are described, 

 and their connection with former and present waters is shown on a chart. 

 The collections, which were made every fortnight from April 16, 1915, 

 to April 1, 1916, contain sixty-four genera and five hundred and eleven 

 species and varieties. These are all enumerated in a general list, which 



