32 0. A r . Rood— Observations on a property of the Retina. 



manent grass land. Nor do we pretend to be able to give a 

 satisfactory explanation of the variations induced, founded on 

 the obvious or recorded difference in above-ground or under- 

 ground character or habit of growth of the individual species. 

 The whole of the results — agricultural, chemical, and botanical — 

 obtained during the twenty years of the experiments are. how- 

 ever, now in course of arrangement for publication; and that 

 we may not overlook such explanations as might be suggested 

 from the point of view of the botanist and vegetable physiolo- 

 gist, as well as that of the chemist, we have associate! with 

 ourselves Dr. Musters in working up the botanical part of the 

 inquiry; and I think Dr. Masters will agree with me in saying 

 that much more has yet to be known of the difference in the 

 physiological capability, so to speak, of the leaves of plants of 

 different species, genera, and orders, and of the differen -e in 

 the distribution, and in the feeding power, of the roots, before 

 satisfactory explanations of the facts observed can be given. 

 Surely, a wide field of investigation for the botanist and' vege- 

 table physiologist is here opened up to view ! 



Art. Ill— Observations on a property of the Retina, fist noticed 

 by Tait; by Ogden N. Eood, Professor of Physics in 

 Columbia College. 



In the Edinburgh Proceedings, 1869-70, vii. p. 605-607, 

 Tait described an interesting observation, which has perhaps 

 some bearing on Thomas Young's theory of color. While suf- 

 fering from indisposition, he noticed each time on awakening 

 from a feverish sleep, that the flame of a lamp seen through a 

 ground-glass shade, assumed a deep red color, the effect lasting 

 about a second. He suggests that the nerve fibiils in the 

 retina also partook of sleep, and on awakening the green and vio- 

 let nerves resumed their function somewhat later than the red. 

 I have m my own case noticed some instances, which seem to 

 point out that after a nervous s/mck, sudden or prolonged, the 

 green nerves (adopting the theory of Young,) recover their 

 activity later than the red, and probably later than the violet 

 nerves. The first observation was made twentv vears ago while 

 recovering from the effects of chloroform, which had been 

 administered by a dentist, well known at that time in Munich. 

 Upon regaining consciousness, and raising my eves to the face 

 •a tor, I was a little surp . previously 



remarked his unusually ruddy complexion, but the next instant 



