232 JOUENAL OF THE ROYAL HORTICULTURAL SOCIETY. 



certainly not a constant feature. An interesting circumstance is shown 

 with regard to the stomata, viz. that the guard-cells have a curious 

 beaked projection on the side facing the other guard-cell. As in Salvinia 

 and Azolla the guard-cells are but feebly cuticularised, but in regard to 

 their shape and beak-shaped projection there is a strong resemblance to 

 those figured and described by Haberlandt in Lemna. The lateral roots 

 which arise from the adventitious roots are arranged in two rows, each 

 root arising from a single endodermal cell. According to Poirault these 

 rootlets do not always reach the exterior at once ; for, having made their 

 way as far as one of the air spaces of the mother root, they grow for 

 some time obliquely downwards before passing through the cortical 

 parenchyma to the exterior. The authoress, however, did not find any of 

 these in her material. The stem of Ceratopteris differs distinctly from 

 that of Pteris aquilina, Trichomanes alatum, Osmunda regalis, and 

 Angioptcris euecta, though up to a certain stage they are the same. " In 

 Ceratopteris the solid stele divides directly into two, whilst in the Ferns 

 described by Leclerc du Sablon (those just mentioned) a ring of xylem is 

 formed by the appearance of pith or phloem in the centre of the solid 

 xylem-strand. No such ring can be detected in Ceratopteris, for the 

 xylem is always present in a central solid mass, and the parenchymatous 

 cells, which may or may not be scattered irregularly amongst the 

 tracheids, can hardly be regarded in the light of phloem or medullary 

 tissue." It is interesting to note that the vegetative buds arise, accord- 

 ing to Heinricher, from a single epidermal cell. He has shown also that 

 the bulbils of some of the Polypodiacece {Asplenium bulbiferum) arise in 

 the same way. King's view of the origin of the Monocotyledons and 

 Dicotyledons is here quoted in this connection. He pointed out that in 

 the embryo of Ceratopteris both the two anterior quadrants form the first 

 leaf, and that from this the stem arises laterally at a later stage. The 

 above groups have in his opinion originated independently of each other 

 from the vascular cryptogams, and he laid stress upon this point which he 

 brings forward as a resemblance betweeh Monocotyledons and the 

 Filicinece. In summarising, the authoress points out that the steles in 

 the stem and leaves are markedly bi-collateral. " In the stem an outer 

 circle of large steles is found, within which small feebly developed steles are 

 scattered irregularly. The stem of the young plant is monostelic, at a 

 later stage the monostele divides directly into two, and further division 

 of the two resulting steles gives rise to the polystelic condition of the 

 older stem." This paper is of special value from the fact that it deals 

 with a Fern necessarily much modified in correlation with its exceptional 

 aquatic habit. It takes a definite place in our rapidly increasing 

 knowledge of special Fern structure. — 11. I. L. 



ClKCUMNUTATION. 



Circumnutation of some Flowering 1 Plants : Comparative 

 Studies. By Elizabeth A. Simons (Contr. Hot. Lab. Phil, ii., No. 1, 

 1898, p. GO). — Experiments undertaken to continue and extend those 

 made by Darwin, on Convolvulus sepium, Phaseolus vulgaris, Lonicera 

 brachyjioda, Wistaria chinensis, and Humulus Lupulus. Undertaken to 



