ZOOLOGY AND BOTANY, miCBOSCOPY, ETC. 243 



wards ; the elevation of temperature of the anthers takes place much 

 later, and is less considerable ; the female flowers experience none at 

 all. The stigmas are mature considerably before the anthers, and the 

 object of the phenomenon is evidently the attraction of insects to 

 assist in cross-fertilization; it disappears as soon as its purpose is 

 accomplished; and the insects are imprisoned by an arrangement of 

 hairs until the anthers discharge their pollen. 



Formic and Acetic Acids in Plants.* — Dr. Bergmann sums up 

 the results of his investigations as to the occurrence and import of 

 formic and acetic acids in plants as follows : — (1) Formic and acetic 

 acids are met with as constituents of protoplasm throughout the whole 

 of the vegetable kingdom in the most various portions of the plant- 

 organism, and both in chlorophyllaceous and non-chlorophyllaceous 

 forms. (2) Formic and acetic acids are to be regarded as constant 

 products of metastasis in vegetable protoplasm. (3) It is probable 

 that other members also of the unstable group of fatty acids, as for 

 instance, propionic acid, butyric acid, caproic acid, or even the whole 

 group, are universally distributed in the vegetable kingdom. (4) An 

 increase of the amount of unstable acids takes place in a plant- 

 organism when its assimilation is interfered with by deprivation of 

 light, i. e. when put into a state of starvation (inanition). (5) Formic 

 and acetic acids accordingly belong to the constituents of retrogressive 

 tissue-metamorphosis. It has been premised that the homologous 

 unstable fatty acids have a similar import in vegetable tissue-meta- 

 morphosis. (6) No increase in the amount of unstable acids takes 

 place in a plant-organism which is withdrawn for a period from 

 the light, under the minimum-temperature required for growth. 



(7) Accordingly the formation of formic and acetic acids in a plant 

 seems to take place to a certain degree independently of respiration. 



(8) Acetic and formic acids are mainly to be regarded as decomposi- 

 tion products of the constituents of vegetable protoplasm. 



Fertilization of Flowers by Insects.f — H. Miiller continues a 

 detailed report of observations on this subject, supplementary to his 

 work ' Die Befruchtung der Blumen durch Insekten,' and defends 

 the above title from strictures brought against it by Behrens and 

 others. 



Influence of the Electric Light on the Development of Plants. J 

 — P. P. Deherain's experiments were made at the Palais d'lndus- 

 trie during the Paris Electrical Exhibition of August 1881. A 

 greenhouse was divided into two compartments, one glazed with 

 blackened perfectly opaque glass, whilst the other was exposed to 

 the ordinary diffused daylight of the Exhibition building. The 

 darkened chamber was illuminated continuously, night and day, by a 

 2000 candle arc-light from a Gramme machine. The transparent 



* Bot. Ztg., xl. (1882). 



t Verhandl. naturhistor. Ver. preuss. Eheinlande u. Westfalens, xxxix. (1882) 

 pp. 1-104 (1 pi.). 



X Ann. Agronomiques, vii. (1882) pp. 551-75. See Journ. Chem. Soc. 

 Abstr., xliv. (1883) pp. 105-7. 



R 2 



