364 THE POPULAR SCIENCE MONTHLY. 



that they move or are retracted under the influence of light, and in a general way 

 indicate by their way of living the possession of some kind of a perception of light. 

 M. Dubois has studied the contraction of the siphon of the PJioIas, and M. d'Arsonval 

 has shown that the muscle of the frog is directly excitable by light. M. G. Pouchet 

 observed that larvae xii Eo-y stalls tenax tried to get out of the light; and as they 

 acted in the same way after their cephalic antennaiform organs had been taken 

 away, he asked whether these buds of future eyes were not ada[.ted to perct-ive 

 light, or whether the fore surface is not possibly sensitive to it. Engelmann found 

 that certain Protozoa moved or remained still according to the character and 

 intensity of the light— not on account of a direct action upon them, but because 

 of the want of oxygen. M. Graber, since Darwin, has shown that the earth-worm, 

 although it has no eyes, is sensitive to light and avoids it, and its sensitiveness 

 seems to reside in its whole body. Finally, M. Loeb has recently made a series 

 of important researches, whence he concludes in favor of a complete identity 

 between the heliotropism of plants and the influence of light on animals, and that 

 a number of blind forms are sensitive to light. The seat of this peculiar form of 

 sensitiveness has not been clearly determined, but is probably in a pigmentary 

 layer under the cuticle. We likewise know nothing certainly of the nature of the 

 sensation. Some think it may be akin to sight, but vague and rudimentary ; while 

 M. Forel would compare it with sensations of touch or of temperature." Photo- 

 dermatic sensibility reaches to the quality as well as the quantity of light, and M. 

 Graher has shown that blind animals prefer some colors to others. But the data 

 on this point do not all agree. 



THE MUSK OX. 



Br HORACE T. MAETIN. 



|UR first introduction to the musk 

 ox {Ovibos moscliatus) carries us 

 back over one hundred and fifty 

 years, when M. Jeremie made his 

 voyage to the northern j^arts of 

 our continent, and, returning to 

 Paris, took with him a sample of 

 wool obtained from an animal he 

 V called the ha>uf musqiie. This 

 '/'^ name was also employed by 

 Charlevoix, writing from Can- 

 ada in 1744. 



Scientists were thus made 

 aware of the existence of a large mammal, 

 which impressed them at once with its eco- 

 nomic value; yet has it refused to come 

 within the range of their keen observation 

 with a persistence unequaled by any animal of its size and im- 

 portance. It was many years later that the first scientific 



