ZOOLOGY AND BOTANY. MICROSCOPY, ETC. 479 



gelatin and plum-juice. Entire seeds of Zea, Hordeum, Helianthus, 

 &c., were carefully washed with a ' 2 per cent, solution of sublimate, 

 and then grown in the prepared substratum. The greater number of 

 cultures remained entirely free from bacteria. The same was the 

 case when pieces of tissue of growing seeds were placed in the same 

 solutions with the same precautions. The general result obtained 

 was that no bacteria are present in living vegetable tissues, and that 

 the fermentative processes in them are due to the vital activity of the 

 cells. 



In the same way M. Laurent demonstrated that the power 

 possessed by germinating seeds of reducing nitrates to nitrites is 

 independent of the presence of bacteria. 



Selective Alcoholic Fermentation.* — According to M. E. Bour- 

 quelot, there is no such thing as real selective fermentation ; in a 

 mixture of sugars each constituent ferments according to its own 

 peculiar laws independently of the other constituents. When yeast 

 is introduced into a mixture of maltose and levulose, or of glucose 

 and levulose, both sugars ferment simultaneously, but at unequal 

 rates. In the first mixture the levulose ferments more rapidly than 

 the maltose, while in the second the glucose ferments more rapidly 

 than the levulose. In both cases, however, at a certain stage in the 

 fermentative process, the order of selection or the relative rate of 

 fermentation becomes reversed. This arises simply from differences 

 in the rate of dialysis through the cell-wall. 



B. CBYPTOGAMIA. 



Cryptogaraia Vascularia. 



Mode of Dissemination of the Spores in Vascular Crypto- 

 gams.! — M. Leclerc du Sablon states that the mode in which this 

 function is effected is the same in all vascular cryptogams except the 

 aquatic Khizocarpeae, viz. by the action of desiccation. 



Taking Polystichum Filix-mas as a type of ferns, the dehiscence 

 of the sporange commences at the spot where the annulus ceases ; 

 this latter gradually straightens, and then curves in the opposite 

 direction. The spores remain attached to the annulus, and are 

 detached and thrown to a distance by its sudden return to its original 

 position. This is the mode of dehiscence of the sporange in all the 

 Polypodiacese, and the process is the same in all essential points in 

 Trichomanes, in Schizsea, in Toclea and other Osmundaceae, and in the 

 Marattiaceae. In the Ophioglossacefe the dehiscence is effected by 

 the unequal tension of the epidermal and subepidermal layers of cells 

 of the epidermis of the sporange. 



In the Equisetaceas the cells of the wall of the sporange have 

 annular or spiral thickenings, and the dehiscence is caused by 

 inequality of contraction resulting from this circumstance. The 



* Comptcs Reiidus, c. (1885) pp. 1404-6, 1466-9. 

 t Aun. Sci. IJfat. (Bot.), ii- (1885) pp. 5-27 (1 pi.). 



