160 



CALIFORNIA ACADEMY OF SCIENCES. 



rather than branching off into the fields where their pro- 

 gress would be impeded by the unevenness of the 

 ground, fences, etc., but if a large body of water should 

 finally interpose a barrier to their course they would, 

 upon reaching it, come to a halt at first while the multi- 

 tude would press on from behind causing a mass at the 

 end. 



This phase would represent a feather with a terminal 

 spot. If the crowd ceased to press on in the rear they 

 would spread along the margin of the water correspond- 

 ing to a feather with a black band at the tip. In this 

 instance the pigment would desert the base of the barbs 

 and spread out into their ends. If a second invasion of 

 the mob occurred later, and it happened that the road 

 along which they were escaping traversed the center of 

 peninsula, the last resort of the people would be to flee over 

 the rough ground in all directions from the road, and 

 we should have first a stage corresponding to a feather 

 with a pigmented border and pigmented center but a 

 clear space between the two, and finally a uniformly pig- 

 mented plume, when the crowd had filled the entire 

 space. Nothing more would remain but for them to 

 pack in tighter and tighter which in the case of the 

 feather would result in the intensification of the color. 

 The accompanying diagram is a conventional represen- 

 tation of these feather changes. 



This example of a mob may seem a fanciful one, 

 and not calculated to prove anything, but indeed it is 



