ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 187 



trial Florideae at present known, in fflwdoclwrton islandicum, a species 

 nearly allied to B. Bothii, forming a dense violet-red felt on the walls 

 and roofs of dry caves. It puts out both erect and horizontal branches, 

 but the latter are not organs of attachment, but simply stolons. 



Rings in (Edogonium.* — Karl E. Hirn has paid special attention 

 to the structure of the rings or cushions which are found in connection 

 with cell-division in the filament of the different species of (Edogonium. 

 Treatment with chemical reagents shows that each cushion is composed 

 of a central mucilaginous mass, surrounded by a coating of cellulose, 

 which does not arise from an infolding of the original cell-wall, but is 

 formed, after the protoplasm has excreted the mucilage, as an inner 

 cell-wall layer, which becomes intimately concrescent with the old 

 membrane above and below the ring. 



Lessonia.f — In Lessonia littoralis Prof. C. MacMillan finds no im- 

 portant difference from other Laminariaceae, either in the structure of 

 the tissues or in the distribution of the sori. The zoned appearance 

 of a section of the stem is due to the increase in thickness being the 

 result of the activity of a hypodermal cambium; this rhythmical growth 

 does not necessarily correspond to an annual period. The species has 

 two kinds of leaf, broader and narrower, of which the former only 

 bear sori. 



Nuclear Division in Spirogyra. f — C. van Wisselingh has continued 

 his researches on the mode of division of the nucleus in Spirogyra, 

 which differs, in several interesting particulars, from that in other 

 plants. The species employed were S. setiformis, and a form nearly 

 allied to S. polytseniata, described as a new species under the name 

 S. triformis sp. n. The fixing material used was a strong solution of 

 chromic acid. 



In S. setiformis the division of the nucleus is never accompanied by 

 the formation of segments, the process differing in some points from 

 that in S. crassa aud in S. triformis, in which respectively 12 and 6 seg- 

 ments are always formed. The form of karyokinesis seems to be always 

 constant for the nuclei of the same filament, as well as the number of 

 segments when segmentation takes place. Whether the filaments remain 

 sterile or conjugate does not affect the process. In S. triformis, when 

 segmentation takes place, of the 12 or 6 segments, 10 or 4 respectively 

 are always formed from the substance of the nucleus, the other two 

 cither from it or from the nucleoles ; for when one nucleole is present 

 it always contains two threads ; when there are two nuclei, each con- 

 tains one. The remaining constituents of the nuclei become absorbed 

 in the nucleoplasm when karyokinesis takes place; while in S. setiformis 

 balls are also formed. 



Multinucleated Cells of Spirogyra.§ — From culture experiments on 

 Spirogyra triformis sp. n. (vide supra), C. van Wisselingh has arrived 

 at somewhat different results from those of Gerassimoff.|| The following 



* Acta Soc. Scient. Fennicae, xxvii. (1900) pp. 4-8 (2 figs.). Cf. this Journal, 

 <inte, p. 65. 



t Bot. Gazette, xxx. (1900) pp. 318-34 (3 pis.). 



t Flora, lxxxvii. (1900) pp. 355-77 (1 pi.). Cf. this Journal, 1899, p. 186. 



§ Tom. cit.. pp. 378-86 (13 figs). || Cf. this Journal, 1892, p. 829. 



