90 



ANDREWS. 



at these points simultaneous or successive strains took effect 

 in different directions. 



Here as elsewhere I find that Butschli has laid down an 

 impregnable basis of fact. I find optical striation to be, as he 

 asserts, associated always with a distinctly linear arrangement 

 of the meshwork substance of a vesicular structure. I find 

 striations like those he describes as typical in his artificial 

 foams, are plentiful and can readily be found in living proto- 

 plasm. It is easy to produce them also in almost any area 

 of the living substance by simple compression, or extension, 

 between cover and slide. The best results are to be had in 

 areas quite but not too viscid. 



I find, beyond this, that there are many conjunctions of cir- 

 cumstance which constrain or impel the mind to strial interpre- 

 tation of an optical network. Some of these seem to be very 

 slight causes, one would think, but the ever too ready mind 

 receives impulse from them, nevertheless, in one direction rather 

 than another, and, moved by such slight matters as relative 

 size, or even difference in geometrical shape, of vesicular con- 

 tours, hastens here or there, shaping lines of emphasis for itself. 

 The accustomed haste of its movements, being now under the 

 spur of enforced attention also, strengthens such an impression, 

 and may conduct the eye in tortuous or broken curves, as well 

 as in more or less straight lines. In some areas, influences such 

 as these urging the mind simultaneously along a number of 

 paths in a given plane, contend with each other, and so pro- 

 duce an aspect of tangled fibrous structure. 



To hold well in leash, without unduly restraining, this eager 

 poise of the mind ; to protect it as much as possible from the 

 vitiating habit of predication which ordinary education and 

 human intercourse teach; these are some of the most necessary 

 and most fruitful lines of self training for those who seek to 

 know the living substance as such. Where the mind follows 

 within the limited depth of focus of the high powers used, it 

 selects from amongst the fused lamellae of the very irregular 

 polygons which at times represent the foam structure, the most 

 obvious and connected paths or lines of the continuous sub- 

 stance ; and a falling of these above or below the plane of an 



