FADING OF MEMORY-TRACES 535 



at once their essential similarity. In the accompanying figure (Fig. 

 47) curve 1 represents the rate of issuance of potassium caseinate 

 from suspended Casein particles into dilute potassium hydroxide solu- 

 tion; 2 represents the rate of extraction of Protamine (salmin) from 

 dried salmon-spermatozoa by dilute hydrochloric acid; and 3 represents 

 the Curve of Forgetting, as illustrated by the results of Ebbinghaus 

 cited above. Comparing these curves it is evident that by a suitable 

 modification of parameters any one of them might be employed in 

 place of the others to illustrate the processes which they severally 

 depict, and that each of them represents the time-relations of a process 

 in which the negative acceleration is so marked as to forbid its repre- 

 sentation by any known chemical reaction-formula, or by the similar 

 formulae which represent the diffusion of crystalloids in fluid media. 

 It has been found that the issuance of a protein (and therefore, probably 

 of other colloids) from a colloidal menstruum is governed primarily 

 by Capillary Forces so that the time-relations of the washing-out 

 process are similar to those exhibited in the rise of a fluid in a capil- 

 lary tube or of a liquid in a column of sand or a strip of filter-paper. 

 We may infer that the fading of a memory-trace is attributable to 

 some similar phenomenon and may not improbably be due to the wash- 

 ing out of a colloidal substance, which forms the memory-trace, by 

 the circulating fluids. This would explain at once the rapidity of the 

 initial stages of forgetting and the extraordinary persistence of the 

 last traces of the memory-deposit, for complete extraction of a colloid 

 from a colloidal menstruum by an external liquid is a matter, not of 

 hours, but, as may be computed by exterpolation from actual measure- 

 ments, may actually require the lapse of periods of time which are 

 vastly in excess of the total duration of the life of man. 



REFERENCES. 

 MEMORY: 



Maudsley: Body and Mind, London, 1873. The Pathology of Mind, London, 1879. 



Munk: Ueber die Funktionen der Gehirnrinde, Berlin, 1881. 



Exner: Pfliigei's Arch., 1882, 28, p. 487. Entwurf zu einer physiologischen 



Erklarung der psychischen Erscheinungen, Wien, 1894. 

 Ebbinghaus: Ueber das Gedachtniss, Leipzig, 1885. 

 Loeb and Koranyi: Pfliiger's Arch., 1890, 46, p. 101. 

 Mosso: Arch. f. Anat. u. Physiol., Physiol. Abt., 1890, p. 129. Phil. Trans. Roy. 



Soc., London, 1892. 183, p. 299. 

 Lepine: Revue de Medicine, 1894, p. 727. 

 Duval: Compt. rend, de la Soc. Biol., 1895, p. 85. 

 Smith: Psychological Review, 1896, 3, p. 21. 

 Bryan and Harter: Ibid., 1897, 4, p. 27; 1899, 6, p. 345. 

 Loeb: Comparative Physiology of the Brain and Comparative Psychology, New 



York, 190C. 



James: Principles of Psychology, London, 1901. 

 Robertson: Arch ; Internat. de Physiol., 1908, 6, p. 388. Biochem. Zeit. Festband. 



f. H. J. Hamburger, 1908, p. 287. Folia Neurobiologica, 1912, 6, p. 553; 1913. 



7, p. 309. 



Gobau: Ann. et Bull, de la Soc. de Med. de Gand., 1910, 76, No. 4. 

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 1901. 



