600 



THE FORMS OF TISSUES 



[CH. 



of the boundary of the system, and to become an island-cell entirely 

 surrounded by the rest. 



Fig. 247. Group of soap-bubbles, blown in Petri dishes, a, b, c, the normal 

 partitioning^ of groups of three, four or five cells or bubbles, d, the three ways 

 of partitioning a group of six cells or bubbles, e, three of the four ways of 

 partitioning a group of seven cells. 



Among the published figures of embryonic stages and other cell 

 aggregates, we only discern the httle intermediate partitions in 

 cases where the investigator has drawn carefully just what lay 

 before him, without any preconceived notions as to radial or other 

 symmetry; but even in other cases we can often recognise, 

 without much difficulty, what the actual arrangement was whereby 



