1904-5.] Niz”s R. FINSEN—HiIs LIFE AND WORK. 109 
was this triumph, a still greater was to be the reward of his unassuming 
genius. 
In 1895 he published a paper which has been as a light in the darkness 
to many an afflicted, hopeless, despairing sufferer, a revelation of many 
a mystery in life’s mystic volume, an interpretation of many a dream of 
the plodding, patient investigator, an inspiration and incentive to all his 
co-workers in this most alluring of scientific fields, the dawn of a brighter 
day. 
Hitherto he has dwelt upon and conclusively proved the irritant 
properties of light in certain conditions and under certain circumstances, 
and shown us how this knowledge may be put to practical use in a negative 
manner, by avoidance. But, as there are always two sides to every ques- 
tion, both of which may be right, so, on this great question of light, he 
throws fresh light, and bids us look on the other side of the picture and 
behold light in a happier mood, ‘‘Light as a Stimulant.’’ In this contri- 
but on, as in the former, one cannot fail to be struck by the humble charac- 
ter of the experiments, contrasting so strangely with the value of the re- 
sults obtained thereby. But as the skilled conjurer performs his most 
wonderful feats with the most homely, insignificant objects at hand, so 
to the true scient’st, often a veritable latter-day wizard, no object in 
nature is too humble to wrest its precious secrets from, and score his 
greatest victories, and lay the world in triumph at his feet. 
And so with Finsen; in observing the development of the eggs of the 
frog, he noted that movements of the embryo were considerably increased 
by the influence of direct sunlight, and that with the eggs of the salamander 
(Triton cristatus) the movements were still more marked. This set him 
thinking. By using coloured glasses, and occasional shading with the hand 
to imitate darkness, he found that the embryos responded more to some 
colours than to others. All sorts of precautions were taken to avoid mis- 
takes, the exact period of exposure to each coloured ray was noted, and the 
exact number of movements, the water in the dish containing the eggs was 
kept cool to avoid errors due to the possible effects of heat rays. The 
result of the experiments proved conclusively that light provoked move- 
ment in the embryos, and that this must be attributed especially to the 
violet rays. 
Next, attention was turned to salamanders an hour old, and others a 
day and a night old. Placing them in a dish of water, their natural ele- 
ment, and placing the dish in the shade, but where a beam of light could 
be reflected upon them by a mirror, it was found that under the influence 
of light they darted ahead, but otherwise remained motionless. Placing 
the dish half in the light and half in the shade, the salamanders moved 
