298 ANNUAL OF SCIENTIFIC DISCOVERY. 



till the end of August, after which it decreases till October ; it then rises 

 again till November, when most of the cultivated flowers are of that 

 color. The green or greenish flowers diminish in number from March 

 till the end of May, and after this the proportion is about uniformly 

 maintained till winter. Blue flowers increase to the middle of April, 

 then decrease to the summer solstice, then ascend to the number reached 

 in April, after which they rapidly decrease, and totally cease on the arri- 

 val of the frosts." The other colors are not regular enough to allow of 

 the giving of a rule for them. 



The author of these observations has arranged the increase and de- 

 crease of the colors in tables, to show them at a glance. It is then seen 

 that each color rises twice and decreases twice. Whenever the white 

 flowers increase, the, yellow decrease, and vice versa. The red and 

 green always correspond, as do the blue and violet flowers. These laws 

 apply to species, not to individuals. 



The same botanist, M. Fritsch, has had the curiosity to examine the 

 corolla of flowers. The number of plants opening their corolla during 

 the night is very small, compared with that of those blossoming during 

 the day, being only about 12 per cent. 



PIASSABA. 



PROFESSOR BALFOUR, at the meeting of the Botanical Society of Edin- 

 burgh, in Jan., gave an account of " Piassaba, a fibrous matter from 

 South America, used for the manufacture of ropes, &c." He stated 

 that the piassaba fibre belongs to the palm tribe, coming from the Cocos 

 de Piacabe of Prince Maximilian. This tree attains a height of 20 or 30 

 feet, and has pinnated fronds 15 or 20 feet long. The fibres of the 

 leafstalks, after maceration, are used for making very tenacious cables, 

 which resist well the action of salt water. The black fibrous matter, 

 resembling whalebone, which is connected with the leaves, has been 

 employed for forming brushes. The fruit of this palm is imported into 

 this country, under the name of Coquilla nuts. The shell or covering 

 of the nuts is used for making many small articles, such as handles for 

 umbrellas, drawers, &c. When examined under the microscope, it 

 exhibits thickened cells, very much resembling those seen in bone. 



THE ACTION OF CARBONIC ACID ON PLANTS. 



PROFESSOR DAUBENY has read before the British Association a report 

 " On the Action of Carbonic Acid on Plants allied to the Fossil Remains 

 found in the Coal Formation." The apparatus used in the experiments 

 made by Prof. D. was so constructed, that a constant supply of 

 carbonic acid could be kept up, so that plants or animals exposed in 

 it were constantly subjected to the same quantities. The results 

 of the experiments were, first, that quantities of carbonic acid 

 not exceeding 5 per cent, did not appear to affect injuriously species 

 of ferns or pelargonium ; second, a quantity amounting to 20 per cent, 

 injured plants exposed to it ; third, the quantity of oxygen given out 

 by plants was not found to be increased by the quantity of carbonic 

 acid to which they were exposed ; fourth, on exposing animals to the 

 action of carbonic acid, it was found that frogs and many fish could 



