546 THE FORMS OF TISSUES [ch. 



urspriinglichsten Schleimblaschen der Pflanzenzelle — ein eckiger 

 Korper gebildet werden, so musste dieser das Rhombododekaheder 

 sein, well dieser- im Hinsicht des Minimums der Masse zu dem 

 Maximum des eingeschlossenen Raumes dem Globus am nachsten 

 liegt. Als die Urform der Pflanzenzelle ist nicht Globus sondern 

 Ellipsoide, daher muss das Dodekaheder, welche die Grundform der 

 eckigen Pflanzenzelle ist, auch aus dem Ellipsoide entstanden sein. 

 Das Rhombododekaheder wird also vom unten nach oben gestreckt, 

 und die Grundform der eckigen Pflanzenzelle ist das in perpen- 

 dicularer Richtung langsgestreckte Rhombododekaheder." 



These views and speculations of Kieser's, now all but forgotten, 

 were by no means neglected in their day. Oken accepted them, 

 and taught them*; Schleiden remarks that "the form of cells 

 frequently passes into that of the rhombic dodecahedron, so beauti- 

 fully determined, a priori, by Kieserf"; and De CandoUe thought 

 it necessary to warn his readers that cells are not as geometrically 

 regular as pubhshed figures might lead one to believe J. 



The same principles apply to various orders of magnitude, and 

 close-packing may be seen even in the inner contents of a cell. In 

 vitally stained "goblet-cells," the mucin gathers into clumps or 

 droplets, of which each appears in optical section to be surrounded 

 by six more. When fixed they draw together, appear in optical 

 section to be hexagonal, and we may take it that they have become, 

 to a first approximation, rhombic dodecahedra§. 



These then, and such as these, were the not unimportant specu- 

 lations on the forms of cells by men who early grasped the fact that 

 form had a physical cause and a mathematical significance. But 

 their conception of the phenomenon was of necessity hmited to the 

 play of the mechanical forces; for Plateau's Statique des Liquides 

 had not yet shewn what the capillary forces can do, nor opened a 

 way thereby for Berthold and for Errera. 



A very beautiful hexagonal symmetry as seen in section, or 

 dodecahedral as viewed in the soHd, is presented by the pith of 

 certain rushes (e.g. J uncus effusus), and somewhat less diagram- 



* Oken, Physiophilosophy (Ray Society), 1847, p. 209. 



t Muller's Archiv, 1838, p. 146. 



X Organogenic vegetale, i, p. 13, 1827. 



§ E. S..Duthie, in Proc, B,S. (B), cxiii, pp. 459-463, 1933. 



