632 SUMMAKY OF CURRENT RESEARCHES RELATING TO 



required in good organic nutritive solution, light being excluded. It 

 loses all its chlorophyll, reduces the stigma somewhat, and passes into 

 the hyaline dark form. 6. The hyaline dark form, a local modification 

 of the green Euglena, can always be converted into the normal form by 

 light. 7. In the light the Euglena shows a delicate green tint after very 

 few hours, produced by the small very numerous chloroplasts. The 

 longer the exposure to light lasts, the deeper becomes the green colour, 

 while the chloroplasts become larger and fewer. 8. The intermediate 

 form suggests an analogy with the higher plants, and shows a variety 

 of types. It occurs spontaneously, but only in albuminous nutritive 

 solution ; is remarkably active, and increases as quickly as the green 

 Eug'mia. 9. In the course of a few weeks, the intermediate form 

 divides into both colourless and normal green individuals. 10. The 

 hyaline light form, which also only appears in albuminous nutritive 

 solutions, is entirely colourless and has no eye-spot. It is evidently a 

 degenerate form. 11. It is a form of quite constant character, and has 

 the power of forming cldorophyll, which it eventually loses. It may be 

 regarded as an apoplastid form, since no degeneration products of 

 chloroplasts nor leucoplasts are to be found. 12. The formation of the 

 hyaline light form arises either through the intermediate, or directly 

 from the green Euglena, the former case representing the extreme of 

 albication — namely, the complete degeneration and resorption of the 

 albicated chromatophores. 



Cultivation of Unicellular Algse.* — A. Hoffmann-Grobety pub- 

 lishes a contribution to the study of unicellular alga in pure cultures, 

 especially the experimental culture of Rliaphidmm minutwn Naeg. 

 (Protococcaceffi). The variations of form presented by the organism 

 under the influence of various alterations in the culture-medium are 

 figured and discussed. An account is given of the experiments made to 

 distinguish two species of algas which are much alike — Chlorella c/elas- 

 troides Chod. and C. ruhescens Chod. Finally the investigations made in 

 connexion with the formation of carotine in Botrydiopsis minor Schmidle 

 are described. 



MicroplaDkton of the Barentz and Kara Seas.t — A. Meunier 

 reports on the microplankton collected during the voyage of the ' Belgica' 

 in the Barentz and Kara Seas ; and adds new records of geographical 

 distribution of Peridiniese, Crytomonadacese, Silicoflagellatge, and Dia- 

 tomaceffi. New genera and species are described. Critical notes are 

 appended to each species recorded, dealing with their morphology, 

 geographical distribution, etc. 



Plankton of Kielkond.J— G. Schneider, E. Taube, and F. Stoll pul?- 

 lish an account of the biological station at Kielkond on Oesel, and this 

 contains a section by Taube on the phytoplankton of the bay of Kielkond. 

 A list of species is given. 



* Bull. Soc. Bot. Geneve, iv. (1912) pp. 73-104 (13 figs.). 



t Due d'Orl^ans, Campagne Arctique de 1907. Bruxelles, 1910. Ch. Beulens, 

 iv., 335 pp. (87 pis.). 



X Arb. Nat. Eiga, N.F., xiii. (1911) pp. 1-52 (1 map and 1 pi.). 



