ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 265 



Algae. 



Phycophsein.* — Herr F. Schiitt has separated this pigment from 

 others with which it is associated in a number of brown and olive sea- 

 weeds from the North Sea : — Fucus vesiculosus, F. serratus, Desmarestia 

 aculeata, Ozothallia nodosa, and others. It can be completely extracted 

 from the living plant by triturating and treating with hot water. 

 The absorption-spectrum of phycophaein presents no strongly marked 

 characters. It exhibits no characteristic bands, but a regular increase 

 of absorption from the red towards the blue end of the spectrum. The 

 pigment appears to be identical in the species examined ; but that from 

 Fucus vesiculosus showed a slightly divergent absorption-spectrum, and 

 slight difference also in its chemical reactions from that obtained from 

 the other species. 



Development of the Thallus of certain Algae. j — According to 

 M. F. Debray, the statement that there is in the thallus of Chylocladia, 

 Champia, and Lomentaria, a single apical cell, is incorrect. The grow- 

 ing point situated at the end of the branches is composed of several 

 independent generating cells placed round the summit. From each of 

 these is formed, by repeated transverse septa, a longitudinal row, each 

 cell of which divides again tangentially into a cortical cell and one 

 lying at a greater depth. 



Sieve-tubes in the Laminarieae. | — Mr. F. W. Oliver describes the 

 occurrence of true sieve-tubes with sieve-plates in the genera Nereocystis 

 and Macrocystis. 



In a transverse section of the stem of any species of Lauiinarieae, the 

 central strand consists of a mesh work of hyphse imbedded in mucilage, 

 among which are a number of narrow tubes, without septa, except at 

 certain points where the hypha is swollen up spherically. Across this 

 enlarged portion runs a septum which is considered to represent a sieve- 

 plate. These tubes are known as sieve-hyphae or trumpet-hyphse, and 

 are universal in all genera of Laminarieae. In Macrocystis and Nereo- 

 cystis, surrounding this central strand of hyphae, is a zone of tubes with 

 thick walls, which are true sieve-tubes, and resemble to an extraordinary 

 degree those of Cucurbita. Callus occurs in both the trumpet-hypha3 and 

 the sieve-tubes of these two genera ; but not, as a general rule, in the 

 other genera of Laminarieae. 



Between the trumpet-hyphaa and the zone of sieve- tubes there run 

 strands of ordinary hyphal tissue. In the trumpet-hyphae, at any rate, 

 the author believes that the callus is formed directly from the cell-wall. 

 In the sieve-tubes sieve-plates occur, not only in the septa, but also on 

 the vertical cell-walls. The callus formation takes place on both kinds 

 of plate, and ultimately completely obliterates the perforations. It is 

 found at no other part of the wall except the sieve-plates, which is not 

 the case with the trurnpet-hyphae. The formation of this callus takes 

 place at an early period in the history of the sieve-tubes. Its properties 

 agree altogether with those of the callus in the sieve-tubes of Phane- 

 rogams. 



The author points out the analogy between the occurrence of sieve- 



* Ber. Deutsch. Bot. Gesell., v. (1887) pp. 259 -74 (1 pi.). 



t Bull. Scient. Depart. Nord, ix., 1G pp. and 4 figs. See Bull. Soe. Bot. France, 

 xxxiv. (1887), Rev. Bibl., p. 160. 



X Ann. of Bot., i. (1887) pp. 95-117 (2 pis.). 



