﻿2 24 BOTANICAL GAZETTE [march 



are composed of two (seldom more) fertile pinnae and a sterile middle lobe, 

 the latter being frequently suppressed. The typical staminate sporophyll of 

 the angiosperms has come from the wedge-shaped or band-shaped sporophyll 

 of the gymnosperms, Anonaceae, Magnoliaceae, Nymphaeaceae, etc. The 

 sporophyte generation of the archegoniates is equivalent to the gametophyte 

 generation, and has arisen from the gametophyte generation through the 

 reduction of the sex organs. The archegoniates came from liverworts or 

 algae, in which the two generations were equal in vegetative work and in 

 .which both generations had the dichotomous thallus. From this condition 

 the sporophyte m the ferns advanced in its development, while in the mosses 

 it degenerated and became dependent. All the Strobiliferae (cone-bearing 

 pteridophytes and gymnosperms) have come from tree ferns of marattiaceous 

 ancestry. The Gnetaceae are related to the Loranthaceae and Santalaceae; 

 Ephedra, however, may be related to Casuarina and Myrothamnus. The 

 Bennettitales are an extinct connecting link between the Cycadales and the 

 Magnoliaceae. From the Magnoliaceae, directly or indirectly, come the rest 



of the dicotyledons, and also the monocotyledons, the latter coming from the 

 region of the Ceratophyllaceae and Ranunculaceae. — Charles J, Chamber- 

 lain. 



The influence of the nucleus upon the growth of the cell is described 

 in a recent paper by Gerassimow.'^ The work is strongly supported by forty- 

 seven tables which record the quantitative relations. Spirogyra was the 

 plant used, and the conclusions depend upon a comparison of the behavior of 

 nucleated and non-nucleated cells. Non-nucleated cells were obtained by 

 disturbing the mitosis so as to move the nucleus from its central position 

 toward one side; on the completion of the partition, one of the cells (in suc- 

 cessful cases) would be left without a nucleus, although its chromatophores 

 and other structures seem to be normal. As is knowm, Spirogyra divides late 

 in the evening or at night, but division may be delayed until morning by 



■ 



lowering the temperature, the division taking place when the temperature is 

 allowed to rise. The writer preferred to use material found dividing spon- 

 taneously. Such material was placed in a suitable vessel, surrounded by 

 snow or crushed ice, and kept near the freezing point for about an hour, but 

 was not allowed to freeze. It was then brought gradually to the room tem- 

 perature. On the following morning many non-nucleate cells and chambers 

 would be found. Although division may be induced by ether, this method 

 was very little used. The following are some of the conclusions : The 

 growth of a cell which has a superabundance of nuclear material is more 

 vigorous than that of the ordinary uninucleate cell. The cell wall, the chro- 

 matophores, and apparently the protoplasm also grow more vigorously. Such 

 cells divide only after they have reached a noticeably larger size. Non- 



" Gerassimow, J. J., Ueber den Einfluss des Kerns auf das Wachsthum der 

 Zelle. Bull. Soc. Imp. Nat. Moscow igoi : 185-220. 47 tables and 2 ph. 



