538 lewis. 



* 



cells in honeycomb. If these cells should be six-sided tubes divided 

 into little boxes by transverse diaphragms, as he described them, 

 octahedral shapes would be produced; though if the diaphragms in 

 adjacent cells stand at different levels, something more complicated is 

 at once suggested. 



In 1812, Dr. Dieterich Georg Kieser, professor of medicine at Jena 

 and collaborator with Oken, obtained the Teylerian prize for an essay 

 on the structure of plants. It seems that he had not then reached the 

 conclusion published in his Phytotomie (1815) that "the higher plant 

 consists of a mass of individual cells — cell-tissue — and the cells 

 then assume, through mutual pressure, a form determined by mathe- 

 matical laws and consequently inevitable, namely that of the rhombic 

 dodecahedron." 2 He considered that this dodecahedron may have 

 the proportions shown in Figure 1, a; or it may be either flattened or 

 elongated (Figure 1,6). In Oken's Physiophilosophy it is declared 

 dogmatically that the fundamental form of cells is the rhombic dode- 

 cahedron, with Kieser as authority; and its production is explained 

 somewhat as follows. If spheres are stacked (after the manner of 

 cannon balls) any one will rest in a depression between three which 

 are below it; it will be surrounded by six in its equatorial region; and 

 there will be three more in contact with it at the upper pole — twelve 

 altogether. The model of such a cell may readily be made from balls 

 of putty or plasticine, which by compression become rhombic dodeca- 

 hedra, and it will be similar to Figure 1, a, but rotated so that trihedral 

 angles are at the top and bottom respectively. Or, following the sug- 

 gestion of Buffon, dry peas may be packed close in a jar and tightly 

 secured by wire netting, after which they are made to swell until all 

 the interstices are obliterated, by placing them in boiling water. The 

 peas so treated are usually irregular little dodecahedra, though peas 

 with eleven or thirteen contacts are not infrequent. 3 



An interesting feature of Kieser's work, often overlooked, is illus- 

 trated in Figure 1, c and d. He considered that truncate rhombic 



2 Although Kieser cites no previous authorities, he may not have been the 

 first to consider vegetable cells as dodecahedral. Allman is said to have made 

 the suggestion, in regard to cells of dicotyledons, in a paper read before the 

 Royal Society in 1811 and privately printed (Thompson, Growth and Form, 

 p. 643). But it was through Kieser's exposition that the idea became gener- 

 ally and favorably known. Thus Schleiden (Miillers Archiv, 1838, p. 146) 

 remarks that "the form of cells frequently passes into that of the rhombic 

 dodecahedron, so beautifully determined a priori by Kieser." 



3 Buffon did not describe the shape of peas, "or better, some cylindrical 

 seed," treated in this way further than to remark that the cylinders become 

 hexagonal prisms. This was in connection with his study of the form of cells 

 in honeycomb. The entire passage has been quoted by Thompson, p. 333-334. 



