The Message of Science. 37 



telligence, begin to develop. Primarily there was but 

 one or two simple thread-like lines of cells attempting the 

 office of transmitting feeling, and succeeding indifferently 

 at first ; but as animals increased in size, the business of 

 telegraphing sensation grew, and a net- work of lines was 

 developed. Sensation was going both ways, and soon the 

 necessity of a common center to which sensory influences 

 could be brought, and thence distributed to their proper 

 destination, was forced upon the nascent, sense-conveying 

 cells, and a ganglion, or little brain, came into existence. 

 The confusion, too, resulting from counter-currents of 

 feeling soon led to the formation of double lines, one for 

 transmitting sensation inward, the other for transmission 

 outward ; and thus the divisions of sensory and motor 

 nerves were inaugurated to and from the little brain 

 center, which presently assumed the function of deciding 

 upon the merits of transmitted sensations, and responding 

 to them by a message from its own sensibility. 



" Nerve ganglia multiplied as animals increased in bulk 

 and attempted larger movements ; and in time, to avoid 

 confusion and get the organic business done, one ganglion 

 was obliged to take the lead and keep order among the 

 other ganglia, to decide between them when they got at 

 variance, and generally to take the office of head ganglion. 



" Thus, in time, a larger and capitally important gan- 

 glion was raised up into prominence to perform the func- 

 tion of oyer and terminer, a cerebellum, and finally a 



