Mak. 1898.] BOTANICAL SOCIETY OF EDINBURGH 113 



developing of these I am indebted to my laboratory 

 assistant, Mr. Wm. M. Miller. 



Explanation of figures of Ajxxli/d lartca, Cornu : — 

 1. Lateral branch beginning below a constriction. 

 '2. Lateral branch lengthening. 



3. General appearance of fungus, showing branching, constrictions, 



granular protoplasm, and two highly refractive cellulin-grains 

 (near the foot of the figure). 



4. Earer form of opposite branches. Observe large celluliu-grain at 



the base of the main filament, and another above the con- 

 striction. 



5. Two pairs of zoosporangia. 



G. Two zoosporangia, superposed, showing attachment to filament at 



base. 

 7. Old zoosporangium, showing germinated zoospores (zoogonidia) 



internally. Obseiwe several cellulin-grains in the other 



filaments. 



The Kklation between the Colour of Daffodils and 

 THE Composition of the Soils in which they are grown. 

 By A. P. AiTKEN, D.Sc. 



(Read 10th March 1898.) 



At a recent meeting of the Society a discussion arose 

 regarding the depth or brilliance of colour assumed by the 

 same species of plant according to a variety of external 

 circumstances, such as the height above the sea-level, the 

 latitude, and the exposure. It seemed probable that the 

 c{uality of sunlight which reached a plant would be most 

 likely to cause colour differences of the kind in question. 

 It was the experience of members of the Society accus- 

 tomed to mountaineering that the colours of many of the 

 commoner flowers found at all altitudes were brighter the 

 higher the level at which they were grown. It seemed 

 probable that this might be attributable to the different 

 quality of light at higher levels where the svin's rays were 

 filtered through a thinner stratum of atmosphere. It is 

 well known that the atmosphere in our latitude not only 

 absorbs fully one-third of the total light that should reach 

 it from the sun, but that it also exercises a selective 

 function in absorbing some of the light rays more than 

 others, viz. those towards the violet end of the spectrum. 

 That such a sifting of light might affect the intensity of 



THAXS. BOX. SOC. EDIX. VOL. XXI. I 



