Literary Notices. cliii 



regards the fact that colored surfaces, when highly illuminated, ap- 

 pear white as a special case of the law of maximal stimulation that, 

 when a stimulus is increased beyond a certain amount, it is not fol- 

 lowed by any increased sensory effect. The upper limit of retinal ex- 

 citation, however, corresponds to the sensation white. 



When common natural pigments are observed spectroscopically, 

 they are seen to transmit broad bands of spectral rays, generally ex- 

 tending to parts of the spectrum other than that part which corre- 

 sponds in color to that of the pigment. Thus a yellow natural pig- 

 ment transmits a flood of red, yellow and green spectral rays. When 

 mixed with red and green, yellow spectral rays do not produce a sensa- 

 tion of their own proper color, but intensify the yellow sensation, 

 which would be produced to a less extent by the intermediate yellow 

 ray, when acting alone. It is a fact, beyond which we cannot go that 

 the combination, red plus green spectral ray, stimulating the eye when- 

 ever we regard a yellow pigment, produces the sensation we call 

 yellow ; an artificial mixture of such spectral rays gives rise to the 

 same sensation. In color mixing experiments, as when you mix a 

 blue and yellow on the discs and produce grey, the blue paper transmits 

 to the eye one-half the spectrum, viz., violet, blue, and some green, 

 and the yellow paper transmits the other half, viz., some green, yellow 

 and red. You are, therefore, looking at what is physically the same 

 stimulus as that given by a piece of white paper seen in half light. 



The statement of the theory is, in its present form, too obscure 

 for criticism, and manifestly brings us no nearer a solution of the 

 physological problems involved. 



Adiposis Dolorosa.^ 



This was reported as a new disease in June, 1892, at the meeting 

 of the American Neurological Association. In many respects it simu- 

 lates myxoedema, from which it would seem'premature to differentiate 

 It until the pathology has been more fully studied. While presenting 

 the appearance of ordinary obesity, it was found that the enlargement 

 was very unequally distributed. Shooting pains were present in all 

 cases at some time. There was diminished cutaneous sensibility in 

 some regions and soreness over nerve trunks in some stages. The 

 connective tissue is largely increased and of an embryonic character, 

 and interfiltrated with fat. The most significant change seems to have 



^ Dercum, F. X. in Supplement to Wood's Reference Handbook of the 

 Medical Sciences. 



