DESIGN FOR A BRAIN 15/2 



depths of the pond, will vary as part-functions. A discontinuity 

 like a surface will generate part-functions in a variety of ways. 



' Now there is a strong mechanical jar — someone throws a 

 stone into the water perhaps.' 



Intermittent variations of this type will cause variations of part- 

 function form in many variables. 



(The Paramecium dives) '. . . this soon brings it into water 

 that is notably lacking in oxygen.' 



The content of oxygen will vary sometimes as part-, sometimes as 

 full-, function, depending on what range is considered. Jennings, 

 by not mentioning the oxygen content before, was evidently 

 assuming its constancy. 



'. . . it approaches a region where the sun has been . . . 

 heating the water.' 



Temperature of the water will behave sometimes as part-, some- 

 times as full-, function. 



(It wanders on) '. . . into the region of a fresh plant stem 

 which has lately been crushed. The plant -juice, oozing out, 

 alters markedly the chemical constitution of the water.' 



Elsewhere the concentration (at zero) of these substances is 

 constant. 



8 Other Paramecia . . . often strike together ' (collide). 



The pressure on the Parameciwri's anterior end varies as a part- 

 function. 



' The animal may strike against stones.' 

 Similar part-functions. 



' Our animal comes against a decayed, softened, leaf.' 



More part-functions. 



'. . . till it comes to a region containing more carbon dioxide 

 than usual.' 



Concentration of carbon dioxide, being generally uniform with 

 local increases, will vary in space as a part-function. 



1 Finally it comes to the source of the carbon dioxide — a large 

 mass of bacteria, embedded in zoogloea.' 



Another part-function due to contact. 



194 



