ZOOLOGY AND BOTANY, MICROSCOPY, ETC. G13 



way, the various movements in the course of development of the organ in 

 question, even in their details. It is then seen how the normal position is 

 attained in the shcrtest way ; and that, in opposition to the theory of de 

 Vries, the excess of weight on one side is, when necessary, counterbalanced 

 by active tensions. The posterior torsion of flowers which become reversed 

 and then again change theii' position, is a necessary resiilt of this theory. 

 The simplest case is that in which no torsion takes place during develop- 

 ment, but where this is attained by median curvature ; and to this all others 

 may be traced. Special cases are treated in detail by the author. 



Floral Conformation of Cypripedium.* — Dr. M. T. Masters first 

 describes the general conformation of orchid flowers, and then that of 

 Cypripedium in particular. The points specially worthy of notice are the 

 lip, the androi'cium, and the gynsecium. The androecium is composed of 

 one median stamen dilated into a broad shield-like staminode, and of two 

 lateral fertile stamens within the preceding. Occasionally pleiomery of 

 the stamens occurs. The author has observed triandrous flowers of 

 C. barbatum and C. Laicrenceanum ; tetrandrous flowers of Uropedium and 

 C. Laicrenceanum; and hexandi'ous flowers of C. Sedeni x« Increase in 

 the number of stamens occurs more frequently in the inner staminal cycle 

 than in the outer. Peloria in Cypripedium, as in other plants, is either 

 (a) regular, or (6) irregular. The author has observed a case of regular 

 peloria in C. Sedeni x ; the usual zygomorphic state being replaced by an 

 actinomorphic condition. Cases of partial irregular peloria in Cypripedium 

 are not uncommon. 



The changes resulting from hybridization among the Cypripedia may 

 be ranged under three categories: — (1) Those in which the changes occur 

 in those characters which are more or less directly of an " adaptive " 

 character. (2) Those in which there is in the offspring a more or less 

 complete reversion to one or other immediate parent. (3) Those in which 

 the change is decidedly teratological, and more or less affecting those 

 " congenital " characters which constitute the symmetry of the flower. 



Cupulas of Cupuliferae.t — Herr L. Celakovsky returns to the earlier 

 view of Hofmeister, that the cupule of the true Cupuliferas is of an axial 

 character. He comes to this conclusion from a comparison of the lowest 

 scales of the cupule of the beech, chestnut, and oak, with the bracts and 

 stipules of the same plants, and from the structure of abnormal examples. 

 The relationships are also discussed between the cupule of the true 

 CupulifersD and the corresponding organ in the Corylaceae. 



Resistance of Pollen to External Influences.:}: — Dr. P. Rittinghaus 

 has made a series of experiments on the power of pollen-grains to resist 

 extremes of external changes. Their subsequent capacity for germination 

 was tested in a nutrient solution of sugar. He finds that most pollen-grains 

 can resist a temperature of 90° C. for half an hour ; the maximum tempera- 

 ture which was found not to destroy life was 104*5° for ten minutes. While 

 low temperatures hinder germination, a lowering to — 20° was found not to 

 be fatal. A moderately high temperature (32') promotes the growth of the 

 pollen-tubes. The protoplasm of pollen is extremely sensitive to antiseptics, 

 usually considerably more so than micro-organisms ; poisonous gases have 

 also a fatal influence. The duration of the power of germination of poUen- 



* Journ. Linn. Soc. Lond., xxii. (1S87) pp. 402-22 (1 pi. and 10 figs.). 

 t SB. K. Bobm. Gesell. Wiss., Nov. 12, 1886. See Bot. Centralbl., xxx. (1887) 

 p. 10. 



X Yerhaudl. Nalurhist. Ver. Preuss. Rheinl., xliii. (1886) pp. 123-66. 



