INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 915 



carbonic acid gas. The amotmt of carbonic acid emitted in respira- 

 tion has no dii-ect connection with that of the oxygen absorbed. In 

 general, at low temperatures, the quantity of oxygen absorbed is 

 greater than that of carbonic acid evolved. There is a certain tem- 

 perature, diflercnt in different species, in which the two amounts are 

 nearly equal ; above this temperature, the production of carbonic acid 

 is in excess of the absorption of oxygen. 



Respiration of Marsh and Water Plants.* — Recent investiga- 

 tions by E. Freyberg have been specially directed to the two facts, 

 that the roots of marsh plants can grow and even flourish in media 

 containing very little oxygen, or even none at all, and that marsh 

 plants are, with very few exceptions, useless to mankind. A series of 

 experiments brought out the fact that marsh plants (rice, Mentha 

 aquaticn, Caltha palusiris, &c.) show a much smaller power of respii-a- 

 tion than land plants belonging to the same natural order (wheat, 

 Lammm album, Banunculus hulbosus, &c.), and consequently require 

 much less oxygen. This low power of resi^iratiou app.ars to be 

 accompanied by a small proi^ortion of nitrogen in their chemical com- 

 position ; a connection dej^ending on well-known physiological facts, 

 the seat of respiration being the protoplasm or albuminoid contents of 

 the cells. In the case of the only two marsh plants which are exten- 

 sively grown as food-material, rice and the sugar-cane, their value 

 depends not on any nitrogenous constituents, but on the presence of a 

 large amount of a carbo-hydrate. 



Influence of Light, Warmth, and Moisture on the Opening- and 

 Closing of the Anthers of Bulbocodium vernum.— Kerner has 

 already observed that the anthers of this plant, belonging to the Col- 

 chicaceae, open in the morning and close in the evening. Mikosch 

 has investigated t the cause of this phenomenon, and attributes it to 

 the action of a special layer which forms the innermost jjortiou of the 

 wall of the anther, and which exists only in anthers possessing the 

 proi)erty of similar movements. This layer consists of three or four 

 rows of cells, compressed from below inwards, the walls of which 

 always remain thin. 



Chemical Eesearches on the Formation of Coal4 — M. Fremy 

 finds, as a result of some laborious and complicated experiments, that 

 the plants which have produced coal have done so by uudergoiu" a 

 process of fermentation, which, in converting them into poat, has 

 completely destroyed every trace of vegetable structure, and it is only 

 when the peat has been subjected to the influences of heat and pres- 

 sure that it has been converted into coal. Coal is not, therefore, 

 an organized structure, as has been supposed. 



With regard to the impress of plant-life which is so frequently 

 to be observed in pieces of coal, M. Fremy suggests that it may 

 be very fairly considered that these marks were made when the 



* ' Landwirthschaftliche Versuchs - stationen,' xxiii. p. 403; see ' Nutur- 

 furscher,' xii. (187^) p. 257. 



t ' Oesterr. Bot. Zeitschr..' June 1878. 



1 'Coinptes Rendus,' Ixxxviii. (1879) p. 1048. 



3 P 2 



