114 SUMMARY OF CUKRENT RESEARCHES RELATING TO 



Morphology of the Flower of Orchideae.* — Prof. E. Pfitzer describes 

 in great detail the structure of the flower of orchids, the result of obser- 

 vations on a very large number of species, chiefly exotic. 



The inferior unilocular ovary he regards as a hollow flower-stalk, down 

 the inner surface of which run the margins of the three carpels as semi- 

 niferous placentas. 



The spur varies greatly in morphological value. We have (1) spurs 

 of purely axial character (Ejndendron, Lselia, Cattleya, Dendrobium, &c.) ; 

 (2) sj^urs which are half-axial {Chaenanthe, Comparettia, Phajus, Sacco- 

 tahiiim, Anectocliilus) \ (3) of purely foliar nature {Disjjeris, Euttonaea, 

 Coryanthes). 



The labellum may be divided into three parts: — hypochilium, meso- 

 chilium, and epichilium. The labellum does not in all cases correspond to 

 the median petal ; one or more of the other petals or the axis may take 

 part in its formation. 



Prof. Pfitzer dissents from the ordinary conception of the column as a 

 product of the adhesion of the upper part of the carpels with one or two 

 fertile stamens, in addition sometimes to two or three staminodes. He 

 regards the column, on the contrary, as purely axial in its character, 

 similar to that of Passiflora, Cleome, and Gynandropsis. There are all 

 stages of transition between orchids with no gynostemium, like Diuris, 

 and those with a long and slender column ; as also between those with true 

 pollinodes and those with ordinary powdery pollen. 



Development of the Flowers and Fruit of Typha and Sparganium.t — 

 According to Dr. S. Dietz the development of the flowers in these two 

 genera, while showing in many respects a general relationship, exhibits 

 such material differences as to justify their being placed in different 

 families. The seed of Tyylia contains a single layer of perisperm and an 

 endosperm composed of several layers ; the long embryo occupying a central 

 position along the axis of the seed ; the small-celled and thin- walled 

 perisperm can only be made out by staining. The detection of the 

 aleurone-grains and nucleus in the cells of the perisperm is also difficult 

 without staining, but the author states that he was able to determine the 

 invariable presence of the latter. 



Pollen of Iris tuberosa.| — Under the name of " Gasparrini's vesicular 

 organ," Sig. G. Licopoli describes a peculiar vesicular structure which he 

 finds in the pollen-grains of Iris tiiherosa, and of some other monocotyle- 

 donous plants. It appears to be nothing but the vegetative cell of the 

 pollen-grain or its nucleus. 



Nectary of Erythroniuni.§ — Dr. S. Calloni describes in detail the 

 structure of the nectary of Eryilironium dens-canis, which does not, however, 

 present any striking peculiarities. Its position is designed to assist in the 

 cross-fertilization of the flower, especially by Hymen ojotera and Coleoj)tera. 



Seeds of Aldrovanda.|| — Herr S. Korzchinsky describes the structure 

 of the seeds of Aldrovanda vesiculosa. The integument consists of five 

 layers: — an outermost black palisade-layer, a delicate sj^iny lamella, an 

 inner brown palisade-layer, a delicate colourless layer, and the innermost 



♦ Pfitzer, E., ' Morphologische Studien iib. d. Orcbidceubliithe,' 139 pp. and 64 figs., 

 Heidelberg, 1886. 



t Bot. Ceutralbl., xxviii. (1886) pp. 26-30, 56-60. 



X Atti E. Accad. Sci. Fis. Napoli, li. (1885) (1 pi.). See Malingbia, i. (1886) p. 36. 



(^ Malpigbia, i. (1886) pp. 14-1) (1 pi.). 



jl Bot. Centralbl., xxvii. (1880) pp. 302-4, 334-5 (1 pi.). 



