G24 EEV. Q. TIEKSLOW ON VERNATION AND EOLIAGE 



in figs. 4 and 5 and 6-8; the last three after dissolution of 

 the crystals in hydrochloric acid. Fig. 6 represents the invest- 

 ment of a large sphere-mass at the junction of four cells ; the 

 support is thicker in fig. 7 ; in fig. 8 it is exceedingly delicate. 



The crystals are composed of oxalate of lime ; they are also 

 doubly refractive. The investing support, if it swells up at all 

 in chloriodide of zinc, does not do so to any appreciable extent : 

 from a mixture of aniline rose and violet, it selects the former, 

 showing that it has somewhat of the character of collenchyma. 



Similar crystals are found in the tissues of the embryo ; but 

 whether they occur in the adult tissue, I cannot say. Mr. Scott, 

 in his memoir on the latex canals of this species*, speaks of clmo- 

 rhombic and sphere-crystals, but is silent as to their attachment 

 to the Avail and investment with cellulose. 



My best thanks are due for aid in prosecuting the above re- 

 searches to the Kew authorities, especially Mr. John 11. Jackson, 

 Curator of the Museums, who has been good enough to supply 

 me with seeds ; to the Royal Microscopical Society, whose 

 Assistant Secretary, Mr. West, has been very helpful ; to Mr. E. 

 M. Holmes, for kindly assisting in the determination of species 

 and communicating specimens of Florideae ; lastly, to Messrs. 

 Fletcher and Davies, of the Mineralogical Department, British 

 Museum, for obligingly looking at my preparations of the endo- 

 sperm of Manihot Gluziovii. 



On Vernation and the Methods of Development of Foliage, ^pro- 

 tective against Eadiation. By the Kev. Geokoe Henslow, 

 M.A., F.L.S., F.G.S. 



[Eead 4th June, 1885.] 

 In his work on « The Movements of Plants,' Mr. Darwin says :■— 

 " The fact that the leaves of many plants place themselves at 

 night in widely different positions from what they hold during 

 the day, but with the one point in common, that their upper sur- 

 faces avoid facing the zenith, often with the additional fact that 

 they come into close contact with opposite leaves or leaflets, 

 ciearly indicates, as it seems to us, that the object gained is the 

 protection of the upper surfaces from beiug chilled at night by 

 radiation." f 



Quart. Journ. Micros. Sc. 1884. t P. 284. 



