384 



THE FOKMS OF TISSUES 



[CH. 



it will be observed that in these figures of Roux's the drops are not 

 always in complete contact, a little air-bubble often keeping them 

 apart at their apical junctions, so that we see the configuration 

 towards which the system is tending rather than that which it has 

 fully attained*. The type which we have called/ was found by 

 Roux to be unstable, the large (or apparently large) drop a" 

 quickly passing into the centre of the system, and here taking up 

 a position of equilibrium in which, as usual, three cells meet 

 throughout in a point, at equal angles, and in which, in this case, 

 all the cells have an equal number of " interf acial " contacts. 



Fig. 170. Aggregations of oil-drops. (After Roux.) Figs. 4—6 represent 

 successive changes in a single system. 



We need by no means be surprised to find that, in such arrange- 

 ments, the commonest and most stable distributions are those in 

 which the cell-contacts are distributed as uniformly as possible 

 between the several cells. We always expect to find some such 

 tendency to equality in cases where we have to do with small 

 oscillations on either side of a symmetrical condition. 



* Roux's experiments were performed with drops of paraffin suspended in 

 dilute alcohol, to which a little calcium acetate was added to form a soapy pellicle 

 over the drops and prevent them from reuniting with one another. 



