612 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Florideae which he has examined (Delesseria, Helminthocladia, Furcel- 

 laria, Polyides), and to fulfil the same function as in the higher plants. 

 The ripe spermatia (pollinoids) were, however, always found to be en- 

 tirely destitute of starch. In Delesseria sanguinea the mid-rib is an 

 organ for the storing up of reserve-substances. Where any part of the 

 plant was uncoloured by the red pigment, this part was always found to 

 contain more starch than the coloured portion. The process of respira- 

 tion is also somewhat more active in the green than in the red portion, 

 but is very feeble throughout the Florideas. 



Nuclear and Cell-division in Dictyota.*— Prof. D. M. Mottier notes 

 the following specialities in the division of the nucleus and of the cell 

 in Dictyota dichotoma. 



The nuclear spindle originates in two systems of kinoplastic radia- 

 tions or asters that lie close to the nuclear membrane and some distance 

 from each other on opposite sides of the nucleus. The radiations of 

 each system are centered upon a very distinct rod-shaped body, the cen- 

 trosome; these together constituting the centrosphere. The centro- 

 some is present during the two nuclear divisions which take place in 

 the tetraspore mother-cell, in the germinating tetraspores, and in all the 

 vegetative cells of the thallus. 



The development of the spindle corresponds closely with that in 

 Stypocaulon. During the prophase of both divisions of the tetraspore 

 mother-cell, the behaviour of the chr jmatin differs strikingly from that 

 of the higher plants. There is not developed here a regular and con- 

 tinuous chromatin-spirem which segments into the chromosomes, but 

 these arise as isolated masses, often differing much iu size. The reduced 

 number of chromosomes, 16, appears in the first nuclear division in the 

 tetraspore mother-cell. The development of the cell-plate or plasma- 

 membrane belongs to the same type as in Stypocaulon, differing both 

 from that in the higher plants, and from those in other families of 

 Cryptogams. No differentiated connecting fibres of any sort can be 

 recognised. 



The author regards the centrosome rather as a special individualised 

 part of the kinoplasm than as a distinct organ like the nucleus. 



Plankton Algae. — Herr E. Lemmermann f gives further results of a 

 series of observations on Plankton- Algae (and Protophyta). In the neigh- 

 bourhood of Berlin he finds the following new species -.—Lagerheimia 

 cctacaniha, Peridinium Marssonii, P. aciculiferum. Cydotella cheetoceras, 

 Synedra actinastroides, S. berolinensis, Merismopedium Marssonii, Nostoc 

 Kihlmani. The mode of formation of the colonies of Bichteriella botry- 

 oides is described, and he identifies with this species Golenhinia feneslrata 

 and G. botryoides. A synopsis is given of the genus Pteromonas, includ- 

 ing the form known as Cryptoglena angulosa or Phacotus angulosus, and 

 5 new species. An account is given of the brackish water phytoplank- 

 ton of the neighbourhood of the Baltic, including 2 new species, Choda- 

 tella Drozscheri and Codospliserium minutissimum. The genera Dinobryon, 

 Mallomonas, Synura, Uroglena, and* Ceratium are wauting. The author 



* Ann. of Bot., xiv. (1900) pp. 163-92 (1 pi.). 

 t Ber. Deutech. Bot. Ges., xviii. (lbOO) pp. 24-32, 90-8, 135-43 (1 pi. and 4 figs.). 



