NOTICES OF BOOKS AND MEMOIRS. 377 



new plants found as there are clusters of leaves on the stem. 

 I may remark, m passing, that I do not remember to have seen 

 ripe seed of this plant ; have any of your readers ? — A. Craig- 

 Christie. 



Plants of Isle of Wight. — Ceratophyllum demersum, Lmn. — 

 The only records of the occurrence of this plant in the Isle of 

 Wight are the somewhat unsatisfactory ones referred to in Mr. 

 A. G. More's Supplement to the 'Flora Vectensis,' published in 

 the 'Journal of Botany' for 1871 (vol. ix., p. 142). It may 

 therefore be of interest to state that it grows abundantly in 

 Westminster Mill-pond near Newport, where it was discovered by 

 Mr. Fred. I. Warner, F.L.S., and myself, on the 18th October. 

 I have been able to find a few staminate flowers only. — Creins 

 taraxacifolia, Thuill. This plant has not been hitherto recorded 

 for the Isle of Wight. I found it growing in an arable field at the 

 south-west side of Totland Bay in September. The upper leaves 

 of my specimens are almost entu-e, with broadly auricled bases, 

 and all the leaves seem to be nearly or quite glabrous. Probably 

 the plant is the variety j^^'^^cox of Koch's 'Synopsis' (3rd ed., 

 p. 374). — Fred. Stratton. 



Erucastrum PoLLicHii. — Tliis plant is of frequent occurrence in 

 this neighbourhood [Saffron Walden] this season ; it grows very 

 abundantly in an old lime-kiln here, and on the road-sides, on the 

 waste ground, and among potatoes and other green c.iops on the 

 chalk land. — J. Clarke, in ' Gardener's Chronicle,' 25th Oct., 1879, 

 p. 534. [This is the species described and figured in this Journal 

 for 1865, p. 165, t. 31 ; we had su^Dposed it long since extinct in 

 Essex.] 



Notttt^ cf ISoolts antr iWtmo(vs. 



Ueher Lichtnirkung tend Chlorophijll-Function in der Pflanze. Von 

 N. Pringsheim. (' Monatsb. der Konig. Akad. cler Wiss. zu 

 Berlin,' July, 1879). 



This paper records the effect of concentrated sunlight on 

 animal and vegetable cells and tissues placed in the plane of an 

 image of the sun, formed with the aid of a heliostat, in the focus of 

 an achromatic lens of 60 mm. diameter. By this means it becomes 

 possible to study the action of light on entire tissues and on single 

 cells, as also on the separate constituents of the cell, to separate 

 precisely the thermal from the chemical action, to determine the 

 nature of this latter action, and to estimate the relative power of 

 diathermancy possessed by the wall of the cell and its contents. 



The author finds that if he puts under the microscope any 

 chlorophyll-containing tissue or single cell, so that it is immersed 

 in the image of the sun, very marked changes occur in from three 



3 c 



