1885.] Fhystology. 3 319 
at which the radiant heat could just be perceived. The relative 
sensitiveness of the skin in different parts is calculated as being 
inversely as the squares of the distances measured. The follow- 
ing table indicates the relative sensitiveness to heat of different 
parts of the skin, the sensitiveness of the palmar surface of the 
third phalanx of the index finger being considered as 100: 
Finger. Dors. Hand, Back. Forearm. Palm. Calf. 
100 204 04 27 294 314 
It follows from the observations made that, “1. The relative sen- 
sitiveness to heat in different parts of the body is not the same in 
different individuals. 2. It differs much less in different parts of 
the same individuals than the sensitiveness to pressure or power 
of localization, the greatest difference for heat being as three to 
one ; while for pressure it is at least as five to one, and for locali- 
zation as sixty to one. 3. The parts in which the other cuta- 
neous senses are most acute are not the same as those in which 
there is greatest sensitiveness to heat. 4. Of the parts examined, 
the tip of the index finger is the least sensitive ; in the other parts 
where the sense of locality is from five to thirty times as dull, 
the thermal sense is from two to three times as acute. 5. The 
thermal sensitiveness bears no definite relation to the thickness of 
the epidermis.” On the contrary the time necessary for an in- 
crease of temperature to be perceived depends directly upon the 
thickness of the epidermis which is heated ( X. Physiology, Vol. 
V; D. 143). 
neg ae and Walton seek to explain temperature sensa- 
tions as the outcome of mechanical stimulation of sensory nerves 
whose endings are submitted to strain due to unequal expansion 
of the two layers of the skin when its temperature 1s changed. 
These authors find that various fresh animal tissues, as tendon, 
expand when warmed, and contract when cooled; others, as elas- 
experiments referred to the temperature was varied between 0° 
and 63°C.—Centralbl. f. Med. Wiss., 1883, No. 32. 
RHYTHMIC CONTRACTION OF THE CAPILLARIES IN Man.—Local 
and obscurely automatic rhythmic contraction of the bloodvessels 
is an established fact. Wharton Jones found that the veins in the 
bat’s wing underwent rhythmic expansions and contractions even 
after there was good reason to suppose that the influence elo 
through the vessels of an excised, but living muscle, undergoes 
alternate acceleration and diminution which can only be explained 
changes in the caliber of the muscular vessels. 
