- Dr, Reuben on Moving Blood- 
6bb.—That the blood-corpuscles, aia or sparse, as in the 
retinal capillaries, can transmit, without appreciable diminution 
of intensity, rays of any color. In this way the coloration of 
the fine parts of images of pictures, landscapes, etc., on the retin 
is aes during our view of the objects, continually interfered 
ae. 
—That moving blood-discs, within the capillaries of the 
retina, according to their form and position, may affect the light 
pases & through them in various ways, by lens-action or total 
re 
—That i images in the retina are variable in their place, 
aun the limits . constituting, on either hand, myopia or pres- 
pia), by minute changes of depth; and are composed of a 
“ ct of solid images of as many colors as the light admitted to 
the eye contains, and more or less perfectly coalescing. 
Moreover, as general facts bearing on the explanation of the 
phenomena now detailed, the following propositions seem to be 
established : 
ece.—That the eye or es in order to discover any of the 
appearances named, must be focused or adjusted for vision of an 
object at some certain ee This necessity of focusing the 
eye explains why, usually, the appearances are so readily lost, 
‘f—That this tak ers for light of placid colors, 
the implied distance of the object being greater or less. Obs 
vations seem to indicate that the distance of the imaginary 
object is least for the red rays, and less generally for the less 
refrangible. 
g.—Hence, when either appearance is seen by merely looky 
ing steadily toward a lighted surface, or until the eye is fati 
itis probable that, involuntarily, the proper focusing or a ind 
ment of the eye takes s place. 
hhh,—With the single exception, if it be such, of the case of 
‘sores steadily at a bright surface, or with the eye fatigued, the 
light with which any of these phenomena i is discovered, is never 
mits or complete light, but always partial, of special colors and 
refrangibiliti ties. 
at is, all the media, or lights, showing these effects, are such 
afford rays of not all, but some certain refrangibilities, All 
toa general facts agree with the Pa Seen that the blood-dises 
become guasi-visible by m eans of their effect as lenses, Although 
tances, the divergency of more refrangible rays which have 
already passed their focus and spread out, (at the very time that 
red and yellow rays have their focal distance and proper effect), 
