428 HENRY H. DONALDSON 



sometimes indiscriminately applied. The cells to which afferent 

 impulses are delivered or between which they pass before they 

 reach the neuron of final discharge, are called correlation neurons. 

 This is the more general term. But the activity of such correla- 

 tion neurons in the cortex is linked with consciousness and these 

 cortical elements are, therefore, distinguished as association 

 neurons. 



Coordination describes the orderly activity of effectors but 

 whether we should distinguish coordination centers as a third 

 class of central neurons seems doubtful, though our author does 

 so (page 181). As matters stand the typical group of coordinat- 

 ing neurons is represented by the cerebellum. It will be noted 

 that the expression reflex circuit has been used in place of reflex 

 arc. The analysis of the reflex by Dewey has drawn attention 

 to the facts on which this change is based. The same afferent 

 axon by its collaterals delivers impulses to the correlation neurons 

 in the region of its immediate entrance into the central system 

 and at the same time by its main axon or other branches to more 

 remote correlation neurons, so that impulses returning from the 

 higher to the lower center find a prepared, rather than indif- 

 ferent, neuron on which to act. A like relation is found between 

 the effector and the central neurons. A circulation of impulses is 

 thus suggested. This is a concept of much value and on it our 

 author lays due stress. 



The convenient term reflex pattern is also utilized. This 

 term, suggested by Sherrington, was applied originally to the 

 form of the functional response to a stimulus, but as such a re- 

 sponse implies a structural basis more or less precise in arrange- 

 ment it is hard to escape the use of the word pattern in the 

 structural sense (p. 312). The term is excellent, but it would 

 be helpful if it could be so modified as to make precise in each 

 instance the sense in which it is applied. In the matter of tech- 

 nical terms the .text follows the B. N. A. except in a few instances. 

 The most notable departure is made in the case of the bundles 

 of fibers which appear in the cross section of the spinal cord. 

 As the analysis of the cord proceeded in the hands of the earlier 

 anatomists, the names applied were largely based on the local 

 relations. The B. N. A. established the general term fasciculus 

 for such bundles, but our author has advanced a step and while 

 retaining the term ' fasciculus " for the bundles composed of 



