M. L. Garreau on the Nitrogenous Matter of Plants. Ill 



XIII. — On the Functions of the Nitroyenous Matter of Plants. 

 By M. L. Garreau. 



[Concluded from p. 43.] 



II. Of the Circulation. 



The intracellular circulation observed by Corti, and since 

 studied by Treviranus, Amici, Robert Brown, Schultz, Raspail, 

 Meyen, Slack, Pouchet, Dutrochet, Schleiden, Steinheil, Bec- 

 querel, Dujardin, Schacht, Trecul, Hugo Mohl, &c, in a small 

 number of plants, has been hitherto generally regarded as a 

 simple motion of rotation, and as peculiar to certain plants. But, 

 from the constant presence of living nitrogenous material in 

 cells in course of growth, the modifications in form that it 

 undergoes, and the vital movements with which it is endowed, 

 and which we shall presently point out in detail, I hope to show 

 that we have not always to deal with a simple act of rotation, 

 and that this movement is as general as the cell. All plants, 

 and their parts, in which the nucleus and its appendages are 

 readily discoverable, are suitable for the study of the vermicular 

 movements of the intracellular circulation; and it is sufficient 

 to select for examination a hair or a thin slice of tissue, in the 

 conditions before indicated, to demonstrate this beautiful pheno- 

 menon. One plant in which it displays itself under the greatest 

 variety of form is the Salvia sclarea. This vigorous labiate plant 

 has its surface everywhere covered over, and particularly its young 

 merithalli, with large hairs, beautifully transparent, and formed 

 by two or three superimposed cells, the septa between them 

 being also perfectly translucent. If a small slice of the hairy 

 epidermis of this plant be examined under water, the canals 

 through which the circulation is carried on are perceived at 

 once in the hairs fringing the section ; and on following atten- 

 tively their course from the periphery, or from any other point, 

 towards the central nucleus, the granules which stream through 

 them may be noticed making their way to the nucleus, whilst 

 some of them are driven against the lateral and opposite por- 

 tions of the canals in which they circulate. The rapidity of 

 these currents is augmented by heat, and varies in each canal : 

 it is almost inappreciable at 10° Cent., but considerable at 25° 

 to 30°; the granules in one stream sometimes traverse the 

 half of the long diameter of a canal in a few seconds, whilst 

 those in others occupy some minutes in accomplishing the 

 same distance. Again, in some canals the circulation becomes 

 arrested for a moment, and sometimes this stoppage is instan- 

 taneous. All these centripetal currents are equally distinguish- 

 able both through the anastomosing canals and through those that 



