412 NATURAL SCIENCE. august. 



probably due to the presence of Benzolaldehyde (oil of bitter almonds) 

 in the floral leaves, judging not only by the smell but also by chemical 

 tests. After a warm sunny day the smell is stronger than after a dull 

 cooler day. When placed in a dark chamber the plant behaves on 

 the first day just as in a light room, smelling only by night, the flowers 

 being closed by day and open at night. But if, in addition, the tem- 

 perature be lowered, the result is different ; thus, specimens placed 

 during the day in the dark near an ice cellar, at one time at 8° R. and 

 another at 1 1° R. (instead of the usual day temperature of 14° — 20° R.) 

 began to smell perceptibly after an hour, although the flowers were 

 only half open, or even in some cases quite closed. To ascertain the 

 influence of light on the formation of the odoriferous substance, the 

 following experiment was made. Specimens with still odourless buds 

 were placed in the dark chamber — in some cases plants in pots, in 

 others cut-off twigs in water-glasses. Other plants were placed in a 

 light room and the parts of the inflorescence with odourless buds 

 covered with dark boxes. The first flowers opening in these dark boxes 

 smelt evidently, though fainter than normally, and it was only after 

 two or three weeks, when the etiolated inflorescence had grown con- 

 siderably in length, that no smell could be detected in the opening 

 flowers ; those opening earlier continued to smell till they withered. 



In the case of plants kept wholly in the dark, the flowers which 

 opened on the first day were scented, but not those opening later, and 

 the former also gradually lost their scent. The single cut-off" flowers, 

 or inflorescences, in the water-glasses lost their smell in the dark 

 chamber after three to four days. In every case the complete dis- 

 appearance of the smell coincided with the complete consumption of the 

 starch in the cells of the floral leaves, only in the stomatal cells could 

 starch-grains be found, and it was possible to foretell with certainty 

 which flowers would open and which would not, by investigating 

 the starch-content of buds in a sufficiently advanced stage of 

 development ; the strength of the smell also depended to a certain 

 extent on the quantity of starch in the floral leaves. As a further 

 illustration of this relation, cut-offshoots of the same Nycterinia were 

 placed in the dark chamber — some in distilled water, some in half per 

 cent, sugar solution. After about four days the former had used up their 

 starch and ceased to smell, but the latter did not lose their starch, nor 

 did the flowers cease to smell till completely withered. Even flowers 

 which had already lost their smell in the dark regained it in sugar 

 solution with the formation of starch in their leaves, while shoots 

 taken from the solution and placed in distilled water in the dark lost 

 their smell as soon as the starch disappeared. As the presence of 

 starch is an index of the activity of constructive processes in the 

 plant, the simultaneous disappearance of the smell of the flowers and 

 the starch from the floral leaves of Nycterinia capensis shows that the 

 formation of the odoriferous substance stands in the closest connection 

 with the life of the plant. 



