SMOOTH MUSCLE RESPONSES 
185 
the muscle had become relaxed and adjusted to the base line the 
salt solution was quickly drained and alcohol in proper concentra- 
tion was added. After the muscle had been stimulated one min- 
ute later the effect of adding the alcohol was recorded in each case. 
The 12.5 vol. per cent concentration (Fig. 13) gives a form of 
curve which we interpret as rather toxic as evidenced by a main- 
tained, prolonged relaxation phase, and the low comparable height 
of the curve when compared to the four succeeding records. As 
the concentration is lowered this factor aparently changes to one 
of sensitization, the contraction phase is increased in height and at 
the same time the relaxation interval is reduced as evidenced by 
the rapid decline of the record. A decided increase in sensitivity 
is evident between concentrations of 9.00 and 6.25 vols. per cent 
(Figs. 14 and 15) but this difference is not quite so noticeable in 
the two lower concentrations (Figs. 16 and 17). 
ETHYL AND PROPYL ALCOHOLS ON THE EARTHWORM 
MUSCLES. 
Several series of experiments were made with earthworm 
muscles using ethyl and propyl alcohols of various strengths, and 
both show decided graded qualitative responses according to con- 
centration. In these experiments care was exercised to have the 
muscle in each case working at its best, that is between the fifth 
and eighth stroke, when the alcohol was added in order to have a 
basis of uniform comparison. Using ethyl alcohol, we have se- 
lected worm 57 as typical of a whole series and we represent two 
normal and the modified response due to various concentrations 
in each of the figures 27, 18, 19, 20, 21 and 22 of plate VII. These 
records were obtained from successive groups of ten somites be- 
ginning with the 3d back of the clitellum. In each case the 7th 
and 8th responses are shown as normal just previous to the addi- 
tion of the alcohol. When 40 vols. per cent was added and 
subsequently stimulated (fig. 27), a response was obtained which 
in height is not more than one-quarter that of the previous normal. 
When 25 vols. per cent was added under precisely the same con- 
ditions, the response was just about one-half of the preceding 
normal, as shown in figure 18. When 10 vols. per cent was added 
(fig. 19) the response was just about equal in height to the pre- 
ceding normal. Figure 20 clearly shows that when 2 vols. per cent 
was added the lesponse outstrips the previous normal by nearly 
one-half its height, while a still weaker solution, 1.2 vols. per 
