i88 3 J 
Eyeless and Blind Animals . 
727 
a peninsula , and is swept alternately by winds from the 
Atlantic and winds from the Mexican Gulf : heats which 
would otherwise scorch her are mitigated. In summer the 
thermometer never rises as high as in the Northern States, 
and in winter it seldom sinks to 40° F. The characteristic 
is mildness and uniformity. 
Winter life amid the balsamic odour of the pines is 
simply delightful. The skies are of softer blue than those 
of Italy. Birds of rarest plumage seek the lakelets, and a 
bird of many songs mocks from pine and orange, and even 
the trellis of your verandah every throat that warbles ; 
and Florida seems an eternal Pasqua Florida — a Palm 
Sunday. 
Washington, D.C., U.S., October 20, 1883 . 
VII. SENSIBILITY TO LIGHT AND COLOUR IN 
EYELESS AND BLIND ANIMALS. 
t CCORDING to the present state of our knowledge it 
is beyond doubt that light, as such, — i.e., unaccom- 
panied by radiant heat, has an effedt upon animals 
not merely by means of the organs specifically developed 
for its perception. It produces physiological changes of 
greater or less intensity in its passage through the skin, or 
through the body in general. For a closer investigation of 
this latter action of light — the “ photodermatic ” — experi- 
mental investigation has not been confined to eyeless spe- 
cies, but parallel researches have been made with blind 
animals. Hitherto most of the experiments upon the acftion 
of light upon eyeless and blind animals have been confined 
to the influence of rays of different colours and intensities 
upon the development of the animals in question. Prof. V. 
Graber, however (in the “ Sitzungsberichte der Wiener 
Akademie ” for 1883, p. 201), has raised the question whether, 
and to what degree, eyeless and blind animals are sensitive 
to differences of light, and manifest this sensitiveness by 
moving towards or away from the light. 
