,g^. NOTES AND COMMENTS. 411 



pseudo-scientists who might be better employed, will prove a serious 

 obstacle to systematic work, and increase the tendency to take up 

 other branches which are not thus hampered, to the neglect of what 

 is by no means the least important aspect of Botany. 



It would be extremely interesting to know what were Dr. Gray's 

 " positive opinions on this point," and why Dr. Britton has not found 

 it in his heart to publish them. 



Observations on the Scent of Flowers. 



In the " Acta Horti Petropolitani," vol. xi., p. 383, Robert Kegel 

 gives an account of some observations made at St. Petersburg on 

 the relation of the smell of flowers to external conditions. The 

 relation is an evident one, but is not the same in different plants. 



Plants whose flowers smell during the day have a much more 

 intense odour in warm than in cold dull weather, thus the Mignonette 

 and Sweet Pea have a much stronger smell on a hot clear day, and 

 flowers of Platantheva hifolia grown in open places are more scented 

 than when sheltered in woods. Flowers of Reseda odorata and 

 Philadelplms covonavius which have already opened and contain 

 ethereal oil smell strongly in the dark, and do not lose their 

 smell in a dark room until they wither. To ascertain whether 

 the ethereal oil can form in the dark, some pots of Reseda odorata 

 and Matthiola incana, with quite odourless buds, were put in a dark 

 room, while others in a light room had the inflorescence only cased in 

 boxes covered inside with black paper and thus kept quite dark. 

 The flowers of the second lot opened and smelt perceptibly, 

 though less than when developed normally in a light room, but in the 

 first case only those flowers smelt whose buds were well advanced 

 when put in the dark, the rest had no smell, and no ethereal oil 

 could be detected in sections of their leaves. Hence it is evident 

 that in these two plants ethereal oil can be produced in the dark at 

 the expense of some nutrient substance which, however, can itself 

 only be developed in the light. 



The flowers of Nicotiana longiflova smell much more at night than 

 by day ; they are open at night and in the morning and evening 

 twilight, but closed by day. After a hot sunny summer's day the 

 smell is more intense than after a dull cool day. When kept in 

 darkness they no longer close by day, and smell both day and night. 

 In specimens of which only the inflorescence was enclosed in dark 

 boxes, all the flowers when opened gave a fairly strong smell ; even 

 when plants were placed entirely in a dark chamber, it was only in 

 flowers that did not open till after three or four weeks that no smell 

 could be recognised. 



Nyctevinia capensis behaved somewhat differently. Here also the 

 flowers are closed and have no smell by day, opening only in the 

 twilight and at night, when they are sweetly scented. The smell is 



