Chap, mi.] of Cell-membrane in Plants. 289 



regular cell-tissue, the shapes of the cells being like geome- 

 trical bodies, in opposition to the irregular tissue of Fuci, 

 Lichens and Fungi. It is a decided improvement on former 

 practice, and one that marks his later works also, that in connec- 

 tion with the structure of the solid cell-fabric he discusses the 

 contents of cells in a special chapter, in which first the matter 

 in solution, then the granular bodies with organized structure 

 are considered, though with the latter he classes not only starch- 

 grains, chlorophyll-corpuscles and the like, but also the sperma- 

 tozoa in pollen-grains and layers of thickening matter projecting 

 on the inside of cell-walls, such as the spiral bands in the elaters 

 of Jungermannieae and several similar formations. He describes 

 the crystals in vegetable cells at some length, and finally 

 discusses the movement of the cell-contents (' sap '), not 

 omitting that of rotation in the Characeae as observed by 

 Corti, and in other water-plants. The chapter on intercellular 

 spaces also shows considerable advance on the views which 

 obtained in 1812; Meyen calls it an account of the spaces 

 produced in cell-tissue by the union of the cells ; the true 

 intercellular passages filled with air are here distinguished from 

 receptacles of secretions, resin-passages, gum-passages, oil- 

 passages, and secretion-receptacles of the nature of cavities. 

 The large air-passages and gaps, such as occur in water-plants, 

 are a third form of intercellular space ; his air-canals in the 

 wood of oak filled with cell-tissue are obviously vessels filled 

 with the substance known as thylosis. The form of the cells 

 in the tissue he thinks is not due to mutual pressure, and he 

 rejects Kieser's view that the ideal fundamental form of cells 

 must be a rhombododecahedron ; but he thinks there is a 

 significant resemblance between the shape of cells and that 

 of basaltic columns. 



In dealing with the spiral tube-system he first discusses the 

 spiral fibre, which appears, he says, either detached between the 

 cells or inside them as well, — an account of the matter decidedly 

 inferior to those of Bemhardi and Treviranus. The spiral 



u 



