MEMOR y. 617 
ical as regards the action of ^lemory. The metaphysician has done but little, 
the physiologist almost everything. 
The most succinct definition of memory I find is Ribot's. He says that : 
" Memory is the retention of certain states, their reproduction and their locahza- 
tion in the past " We certainly cannot wish for a more clear analysis. Physi- 
ologists have located the intellect in the gray matter of the brain, a thin crust 
one-tenth of an inch thick and composed of convolutions and sulci. It has been 
estimated that there are about 300 square inches of gray matter upon both hemis- 
pheres. This crust is supported by white matter which is a mass of nerve fibres, 
and makes by far the largest part of the brain. The gray matter is composed of 
cells and fibres, which according to Mr. Bain, number about one billion and five 
billions respectively. These cells and fibres are the factors of memory, and for 
distinctiveness at this time I will denominate them memory-cells. 
An acquisition is a certain thing acquired or learned, and in a richly en- 
dowed and highly retentive mind of, say, two hundred acquisitions, each group- 
ing would require five thousand memory-cells and twenty-five thousand fibres. 
It must be remembered, that the brain, besides having memory-cells and their 
associated fibres, is also a sort of battery to furnish power for movements of mus- 
cles, acts of energetic volition, and also of feeling. 
The causation of memory is just as mysterious as that of life. Memory 
exists and that is the sum total. Life was brought into existence, either from a 
fortuitous combination of oxygen, nitrogen, hydrogen and carbon, making pro- 
toplasm, which became animated, or by a special divine act of creation. Scien- 
tists generally agree that all life must have antecedent life, which to my mind is 
the only proper solution of biology. 
The two most plausible theories which account for memory physically, are 
the residua and vibratory. According to the former theory, when an impression 
is received by a cell, a residuum is left, the result of a chemical change or decom- 
position of its protoplasm. When we look upon a pear, certain cells respond to 
the excitation of the impressions of contour, color, size, and stem ; the result of 
this responding is a residuum. If these impressions are repeated often enough a 
permanent residuum is formed and we have a memory-cell. Decomposition is the 
act of separating the constituents of a compound. These constituents would be 
elementary bodies, but m the above cells, the decomposition is said to leave a 
residuum, but no explanation is given, as regards the action of the residuum after 
it is formed. I am at loss for any logical deduction whereby I can understand 
the action which goes on in the cell after it has been completely decomposed and a 
permanent residua has formed, which under this theory I would call a memory- 
cell. The jesidua theory leads us to the time when the cell becomes permanently 
changed, but does not enlighten us upon its subseqent action. 
The vibratory theory explains the physiological action of memory in a 
very satisfactory manner. If we look at the pear, certain cells vibrate from 
excitation, resultant from the impression. We do not have, in this instance, 
any decomposition or residuum, simply a vibratory movement. The cell remains 
