Word: frogs
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...University laboratories these investigations have now been pushed much farther and made more exact. The recent experiments were performed upon the eyes of frogs. The frog was killed and his eye was then immediately removed. The eyeball was cut in two and the optic nerve, which ordinarily connects it with the brain, was attached instead to two electrodes connected with a vacuum-tube amplifier such as is used in wireless telegraphy...
This was connected with a string galvanometer so adjusted that it registered the slightest electrical disturbance. In other words, whatever the frog's eye "saw" was reported electrically, not to the frog's brain, but to this galvanometer, and amplified 500 times...
This apparatus, attached to the frog's eye, proved far more sensitive to light than any hitherto constructed, showing that the eye is a more sensitive instrument than any which it has been possible for man to construct. It measured the impulse from light a great deal too faint for ordinary human vision. The galvanometer, for instance, registered a stimulus from the light, as faint as would be that of a candle set 1200 feet away from the frog's eye, and did this, furthermore, with the front of the frog's eyeball cut off so that there...
White light, for instance, when flashed from the frog's eye, causes impulses to pass along the optic nerve to the galvanometer in groups, while blue light causes regularly recurring impulses. As the investigators alter the color of the light cast upon the frog's eye, the rhythm of the impulses varies accordingly. Incidentally, it has been noted that the frog is practically red blind; the frog's eye transmits only very faint impulses from red light...
...Harvard Zoological Club. "Effect of Narcotics on Respiration in Frog Tadpoles," by Miss Marian Irwin. Zoological Laboratory, Room...