266 SUMMARY OF CURRENT RESEARCHES RELATma TO 



In some instances it is composed of two sets of cells, those springing from 

 the centre not reaching the margin, and those springing from the margin 

 not reaching the centre. 



Herr Bachmann describes the peculiarities of these hairs in the various 

 species examined, and discusses the value of characters derived from them 

 for the purpose of classification. 



Zygomorphy of Flowers.* — Herr H. Yochting distinguishes three dif- 

 ferent sets of causes as producing zygomorphy in flowers, viz. : — (1) Gravi- 

 tation only, (2) gravitation acting on the constitution of the organs, (3) the 

 constitution of the organs alone. In the first type, which he terms zygo- 

 morphy of position, the flowers are always at first actiuomorphic or regular, 

 becoming subsequently zygomorphic. In all the plants examined belong- 

 ing to this type, with the exception of Epiphyllum truncatum, the flowers 

 are lateral, and all the members of the same whorl are affected by geo- 

 tropism of the same kind, positive or negative. In that species the flowers 

 are terminal, and it exhibits in other ways exceptional phenomena. Closely 

 connected with the form of the flower is the curvature of the flower-stulk. 

 Plants very closely allied to one another exhibit the greatest differences in 

 the mode in which their zygomorphy is manifested. The curvature of the 

 stalk is sometimes the result of inner, sometimes of outer causes ; and with 

 the same origin on the axis, and the same horizontal position of their own 

 larger axis, the flowers are sometimes actiuomorphic, sometimes zygo- 

 morphic, the latter property being sometimes produced by gravitation, 

 sometimes by internal causes. 



Double Flowers. f — Herr K. Goebel discusses the question of the 

 doubling of flowers, chiefly from a horticultural point of view, and gives the 

 results of a large number of observations. These observations, chiefly those 

 made on Leucojum, show that from stocks with single flowers, seeds can 

 be obtained by selection which will produce a larger and larger propor- 

 tion of individuals with double flowers up to even 90 per cent, or still more ; 

 and from this he draws the conclusion that there must be a tendency 

 towards doubling in the seeds borne by single flowers. The seeds which 

 will produce double flowers can be distinguished by their smaller size and 

 abnormal forms, from those which will produce ordinary single flowers. 

 The various modes of doubling are described, resulting from the reversion 

 of stamens to the condition of petals and from the increase in the number 

 of petals or of corolline whorls. 



Ovuliferous Petals in Caltha palustris.| — M. L. Mangin calls attention 

 to examples of flowers of this plant possessing two small supplementary 

 petals [sepals] within the ordinary ones, which bore on their margins 

 one or two rows of small buds. Each of these buds consisted of a nucellus 

 protected by an integument and containing an embryo-sac, in which could 

 be detected an oosphere, two synergidae, antipodal cells, and a vegetative 

 nucleus. 



Inferior Ovaries.§ — Herr K. Goebel discusses the two views as to the 

 development of the inferior ovary : that of Koehne and Van Tieghem, 

 that it is the result of coalescence of the basal portions of the sepals, and 

 that of Schleiden, Payer, Hofmeister, and Sachs, that it arises from a 

 hollowing out of the receptacle before the foliar organs have begun to be 



» Pringsheim's Jahrb. f. Wiss. Bot., xvii. (1886) pp. 297-346 (5 pis.)- Cf. this 

 Journal, 1886, p. 472. 



t Pringsheim's Jahrb. f. Wiss. Bot., xvii. (1886) pp. 207-96 (5 pis.). 

 + Bull. Soc. Bot. France, viii. (1886) j.p. 262-3. 

 § Bot. Ztg., xliv. (1886) pp. 729-38 (1 pi.). 



