H. BOTANY AND HORTICULTURE. 365 



starting-point for similar monographs of other divisions of 

 the fossil plants of America. 



Professor Lesquereux gives an account of the circumstances 

 under which this formation was discovered and explored by 

 Dr. Hayden and others, and then considers the surface and 

 stratigraphical distribution of the species. In accordance 

 with Dr. Hayden's views, the author finds the group to be 

 of marine origin, as shown by the occurrence of various spe- 

 cies of marine mollusks. 



Numerous important general considerations are presented 

 by Professor Lesquereux in connection with his subject, and 

 in the concluding part of the memoir he remarks that he is 

 not prepared to commit himself in regard to the correlation 

 of the flora of the Dakota group with that of subsequent 

 geological epochs, and their identity, preferring to wait the 

 gathering and examination of other series. He, however, 

 states that this flora, without affinity with any preceding 

 vegetable types, without relation to the flora of the lower 

 tertiary of the United States, and with scarcely any forms 

 referable to species known from coeval formations in Europe, 

 presents, as a whole, a remarkable and, as yet, unexplained 

 case of isolation. 



ABSORPTION OF OXYGEN BY PLANTS IN THE DAEK. 



According to Deherain, leaves kept in a confined atmos- 

 phere, in darkness, will absorb the whole of the oxygen, and 

 still continue to give off carbonic acid, the resistance to as- 

 phyxia varying with the species. The rapidity of growth 

 and energy of respiration of plants are both favored by ob- 

 scure heat ; and it is shown that the internal combustion, by 

 the absorption of oxygen and emission of carbonic acid, is 

 the origin of part of the heat necessary to the elaboration of 

 new proximate principles in the plant. 21 A, Sept., 1874, 910. 



TRANSFER OF THE ALBUMINOIDS OF THE SEED INTO THE 



PLANTLET. 



It is a familiar fact that germinating plants derive their 

 nutrition from the reserve materials in the cotyledon, and 

 that the insoluble starch of the latter is converted, in the 

 process of germination, into soluble sugar, and, as such, trans- 

 ferred to the new plantlet. Some late German investigations 



