THE HEXAGONAL PRINCIPLE. 



363 



that the cell is made hexagonal by the cutting away of mate- 

 rial from six surrounding cells — they both agree in one point, 

 namely, that the normal shape of the cell is cylindrical, and 

 that it only assumes the hexagonal form by mechanical means. 



MISCHOCYTTARUS. 



RAPHIGASTER. 



These questions were briefly mentioned, because an entire 

 omission of them would appear negligent, but they were not 

 followed up because the nests that would set them at rest be- 

 longed to another group. We will first take the central nest. 



