172 Literary Notices. 



former case more, and in the latter case less, nervous energy is simultaneously con- 

 ducted to the brain. A similar activity goes on in the cerebral neurones, but here 

 when the resistance is raised the energy that passes through is transformed, the 

 author seems to mean, into consciousness; just as a highly resisting wire transforms 

 electricity into heat. A lower resistance in the cerebral neurones allows more 

 energy to pass through while less is allowed to contribute to consciousness. The 

 author says that the cerebral cells "do mostly not function to conduct the energy 

 which flows to them and to send it on to stations beyond; but they are themselves 

 end-stations in which 'sensation' is produced." The author says, however, 

 "Yet there is a large variety of phenomena in human consciousness which points to 

 the fact that a cell which just now meditated a sensation, may in the next moment 

 assume a wholly different function; that is, in many cases it is not at all the duty of 

 a sensory cell to feel, but rather to 'conduct.' We have only to call to mind our 

 'subcortical' activities." The author then goes on through the rest of the paper, 

 amidst a host of assertions that the physiologist must account hazardous, to say 

 the least, to develop his theory of all-centripetal nervous impulses; The main 

 value of these speculations probably lies in the emphasis given to probable changes 

 in the conducting power of the neurones that mediate consciousness, for which 

 indeed there seems to be considerable empirical evidence. The author seems quite 

 to follow Professor Ostwald's view that consciousness is a form of energy. He 

 offers no explanation for the spontaneous powers ascribed to the spinal and cerebral 

 ganglion cells. It seems probable that this would be his physiologic explanation 

 of free will. 



Piper, H. Beobachtungen an einem Fall von totaler Farbenblindheit des Netzhautzentrums im einen 

 und von Violettblindheit des anderen Auges. Zeitschrift f. Psychologie u. Physiologie der 

 Sinnesorgane, Bd. 38, pp. 155-188. 1905. 



In the present case Piper found violet color blindness in the fovea of the left 

 eye and total color blindness in that of the right eye. For the left eye a match for 

 every monochromatic light of the spectrum could be found either in other unmixed 

 monochromatic lights or in mixtures of two, one of short wave-length (500«/«) and 

 the other of longer wave length (S^Ofiji). The curves for the relative quantities 

 of all such lights, necessary to match the successively presented monochromatic 

 lights, correspond closely to the first two curves (red and green) for normal vision; 

 the third normal curve is wholly lacking. The case is, therefore, one of violet 

 color-blindness, and is easily explicable by Helmholtz's triple-component theory. 



In the totally color-blind right fovea the distribution of brightness in the spec- 

 trum tallied with that for normal "day-vision" (brightest in orange-yellow), but, 

 for the whole eye, when dark-adapted, with that for normal "twilight-vision" 

 (brightest in green). This is the first time that tliis difference in central and periph- 

 eral brightness-distribution has been observed in the same eye, undisturbed by the 

 presence of color vision, and it supports in a striking way v. Kries's "Duplizi- 

 tatstheorie"; i. e., that the cones mediate colorless sensation in "day-vision" 

 and the rods in "twilight-vision." The facts are incompatible with Hering's 

 assumption of the specific brightness of colors, because that cannot be present when 

 the colors are absent, and yet Hering introduced the conception to explain this 

 very difference between "day" and "twilight" vision. The phenomena are, 



