188 SUMMARY OF CURRENT RESEARCHES RELATING TO 



arc the chief points in which his conclusions differ from those of the 

 previous observer. 



By the method of culture employed, in glass vessels, a uninucleated 

 gave rise to a binucleated cell when karyokinesis took place, but the 

 formation of septa was partially or entirely suppressed. In the multi- 

 nucleated cells the nuclei lay in the axis of the cell, as in the normal 

 uninucleated cells. No specially large or compound nuclei were obtained. 

 When karyokinesis was repeated in the binucleated cells, and the forma- 

 tion of septa still suppressed, cells with 3, 4, or more nuclei were 

 obtained. < 'ells with 1, 2, 3, 4, or more nuclei occurred in the same 

 filament, and the number of nuclei did not affect the thickness of the 

 filament. No evidence was obtained of an hereditary transmission of 

 the abnormal condition. The phenomena were not necessarily con- 

 nected with a retardation of karyokinesis. 



Branching of Cladophora and of some Monosiphonous Algae.* — 

 M. Nordhausen regards the basal branching of the cells in a filament of 

 Cladophora as a peculiar process, to which there is nothing strictly com- 

 parable in other Algae. In monosiphonous Algae — Ceramium, Griffithsia, 

 &c. — the angle made by branches of the same order varies in size ; it 

 increases, on the whole, towards the base of the plant. This difference 

 is the result of a constant variation in each angle. These changes 

 follow a distinct law, and are dependent on processes of growth con- 

 nected with the life of the plant, especially with its growth in thickness. 



Polarity and Regeneration of Bryopsis. — H. Winkler f criticises 

 Noll's explanation \ of the fact that the reversal of the position of a 

 filament of Bryopsis muscosa converts the aerial root into a rhizoid, and 

 vice versa. He refers it to heliotropic influences rather than geotropic, 

 as Noll does. 



Replying to this paper, F. Noll § says that Winkler's conclusions 

 and his own are not out of harmony. He further points out the con- 

 fusion that arises from the use of the term cell both for a dead 

 structure and for a mass of living protoplasm inclosed in a cell-wall. 

 He proposes to adopt Sachs's term " energid " for the latter, retaining 

 Kolliker's term " protoblast " for the protoplasmic constituent of an 

 energid. An energid is bounded by a single continuous parietal utricle, 

 and may be uninucleated or multinucleated. 



Nuclei of the Lower Algae. — Prof. R. Chodat and Mile. Cretier 

 have determined the position of the nucleus and pyrenoid in a number 

 of the lower green Algae. A plurality of pyrenoids was observed in 

 Raphidium pyrenogerum sp. n., but this does not carry with it an increase 

 in the number of nuclei, of which there is only one. In Actinastrum 

 the original position of the nucleus is central ; on division it becomes 

 basilar in the daughter-cells, and divides laterally (longitudinally) in 

 this position. In Botryococcus there is also one nucleus in the cell, but 

 the chromatophore contains a smaller body resembling a nucleus, but 

 which is rather a pyrenoid without an ainylosphere. The same is the 

 case with Hydrurus. 



* Pringsheim's Jahrb. f. wiss. Bot., xxxv. (1900) pp. 366-405 (1 pi.), 



t Tom. cit., p. 449 (3 figs.). J Cf. this Journal, 1889, p. 421. 



§ Ber. Dtu'sch. Bot. Ges., xviii. (1900) pp. 444-51. 



II Arch. Sci. Phys. et Nut., x. (1900) pp. 387-8. 



