LIFE OF THE PLANT-CELL. 



113 



to the cell-walls from which they are secreted. The 

 latter circumstance appears to me to be decisive of 

 their nature as a product of secretion. 



Lastly, upon examining the same formations in 

 Justicia carnea, in a longitudinal section (fig. 101.), 

 the secreted substance is seen to be continuous 

 throughout the whole length, between the rows of 

 cells, and presenting only indistinct traces of divi- 

 sion. 



The history of the development of these forma- 

 tions is at present deficient. Mohl's * earlier opi- 

 nion, according to which the intercellular substance 

 is said to be the remains of the primordial ma- 

 terial in and from which the cells are formed, I 

 consider decidedly incorrect, and to be contra- 

 dicted by Meyen'sf discovery of the division into 

 portions of the intercellular substance. He has 

 himself also, perhaps, since then relinquished this 

 notion. 



It appears, however, to me that, to the above de- 

 scribed formations in the external cortical layer in 

 the families mentioned, and some others, other dif- 

 ferent but analogous forms must be referred, par- 

 ticularly the cells of the cotyledons in Scholia 

 speciosa and latifolia, Tamarindus indica, and some other Leguminosce, 

 as well as the very similar formations between the angles of the epider- 

 mal cells in many species of Begonia, and of the leaf-cells in several 

 Junyermannice. In these instances, also, a triangular intercellular space 

 appears to be filled with a substance secreted from the three cells form- 

 ing its boundaries, as has been also observed by Meyen J in Begonia. 

 Of some formations (particularly those in Schotia and Jungermannice), 

 Mohl has now offered an explanation similar to that which he gives of 

 the secreted layer in the epidermis, viz., that the cells are thickened by 

 a laminated deposit on the internal surface, in consequence of which the 

 outer layers must necessarily constantly undergo a change in their 

 chemical nature, for in all these formations the apparently perfectly 

 continuous cell-membrane bounds the cavity of the cell. How far Mohl 

 is inclined to extend this view of his to other conditions, I know not. I 

 must confess, that the view propounded by Meyen at present appears to 

 me to be inadmissible. As yet, however, a complete history of the de- 

 velopment of these structures is wanting, to enable us to arrive at a more 

 certain conclusion. 



The semi-fluid gelatinous matter which occurs in the intercellular 

 spaces of the albumen of the Cassice and other Leguminosce, between 

 the cells of the Lichens, especially of the utricular layer, but, above 

 all, in the intercellular spaces of the Fucoidece, which latter very 

 nearly approaches dextrin (?), presents a manifest transition from the 



* Erlauterung und Vertheidigung meiner Ansichten uber Pflanzensubstanz, &c. 

 f Physiologic, vol. i. p. 170. J L. c. 



101 Longitudinal section through the outer cortical layer of Justicia carnea; perpendi- 

 cular rows of cells with chlorophyll granules, intercellular substance, secreted on both 

 sides of the intercellular passages. 



