ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 1015 



large number of flowers belonging to many different orders of Exogens 

 and Endogens. He finds tbat it always has reference to the mode of 

 fertilization, and especially to the position of the stamens. As a rule, 

 terminal flowers, or those on long stalks, are regular, or at least, not 

 zygomorphic, and have the nectaries arranged in a regular whorl in 

 the centre. Lateral flowers are generally irregular and zygomorphic, 

 and the nectaries are either exclusively or chiefly on that side of the 

 flower on which the insect seats itself. Special contrivances are de- 

 scribed for bringing the anthers near to the nectary at the time that 

 they are discharging their pollen. Sometimes they change their 

 mode of dehiscence in course of development from introrse to 

 extrorse by a torsion of the filament. 



Functions of Chlorophyll.* — M. C. Timiriazeff gives a review of 

 the present state of our knowledge on this subject. He first of all 

 points out the source of error in the observations of Draper, Pfeffer, 

 Mliller, and especially of Keinke, from the use of too wide a slit, which 

 causes impurity of the spectrum. If a sufficiently narrow slit is used, 

 it is demonstrable that the maximum of decomposition occurs in the 

 red rays, and not in the yellow, as was formerly maintained. By the 

 use of the spectrogram method, it can be shown that chlorophyll 

 is a compound of two immediate principles, the green chlorophylline, 

 and the yellow xanthophyll. M. Timiriazeff further explains the 

 micro-eudiometric method by which so small a quantity as O'OOOl 

 c.cm. of gas can be easily measured. The chief function of chloro- 

 phyll, or rather chlorophylline — for the xanthophyll takes no part 

 in it — in the decomposition of carbonic acid, may be stated to be to 

 absorb the rays which possess the greatest energy — being transparent 

 for these energetic rays — and to transmit this energy to the molecules 

 of the carbonic acid which would not of themselves undergo decom- 

 position. 



Apical growth of Gymnosperms.t — In opposition to the views of 

 Groom and Schwendener, Herr H. Dingier maintains the general 

 agreement of the mode of growth of Gymnosperms with that of 

 Angiosperms, from a single apical cell. In a number of cases a well- 

 marked tetrahedral apical cell with two or three segments can be 

 readily recognized ; in others various arrangements of cells are 

 exposed by a superficial section, the explanation of which is not clear, 

 but he thinks that these cases can also be referred back to a single 

 apical cell. 



Resting-periods of Plants.J — Herr H. Miiller-Thurgau discusses 

 this subject at length, and maintains that the winter period of rest of 

 many plants is not dependent on external conditions such as tempera- 

 ture or moisture, but on internal changes, and especially on such as 



* Ann. Sci. Nat. (Bot.), ii. (1885) pp. 99-125 (6 figs.). Cf. this Journal, ante, 

 p. 281. 



t Ber. Deutsch. Bot. Gesell., iv. (188G) pp. 18-36 (1 pi.). Cf. this Journal, 

 iv. (1884) p. 408, v. (1885) p. 487, ante, p. 470. 



X Landwirths. Jahrb., 1885, pp. 851-907. See Bot. Ceutialbl., xxvii. (1S8G) 

 p. 90. 



