384 KANSAS UNIVERSITY SCIENCE BULLETIN. 
isotonic Ringer solution. This was then siphoned off and re- 
placed by the special salt which was to be studied. In no case 
was the same strip used twice. It was interesting to note that 
strips from some frogs when suspended showed peristaltic 
action, while those from.others did not. But as soon as the 
salts were added the peristaltic movements either decreased 
or ceased. The period of action of each solution was limited 
to about eight minutes and was followed in each instance by 
an isotonic Ringer solution. I did not attempt to determine 
whether the observed effect of the salt was upon the muscle, 
contractile tissue or nerve sells or nerve endings. 
After many trials an isotonic indifferent Ringer solution 
was secured, in which the moist strip neither relaxed nor con- 
tracted, but continued its peristaltic movements. The follow- 
ing solutions were then employed in the experiments: the 
influence of, first, slight alkalinity; second, slight acidity of 
Ringer solutions; third, NaCl in strengths from m/32 to m/8; 
fourth, KCl from m/64 to m/8; fifth, CaCl, from m/64 to m/8; 
sixth, MgSO, from m/32 to m/8; seventh, BaCl, from m/64 
to m/8. Also, the influence of tap water and double-distilled 
water were determined. 
I might state at once that tap water caused a marked con- 
traction, possibly due to the large percentage of calcium, while 
double-distilled water had an opposite effect, namely, that of 
relaxation, probably due to the extraction of salts from the 
tissues. This corresponds with Meigs’ and McGill’s results 
on smooth muscles from the stomach of the frog with hypo- 
tonic solutions. 
The accompanying plate illustrates characteristic curves 
from the different solutions and their most pronounced effects. 
A neutral Ringer solution was made .04 per cent alkaline by 
adding Na.Co, to it. In this solution the peristalsis ceased at 
once, and the contraction reached its height within a half 
minute. Though the per cent of alkalinity was small, the 
effect was quite marked, producing contractions in each case. 
In a .04 per cent acid Ringer solution, made so by adding 
HCl, peristalsis ceased at once, and within a half minute 
reached its limit of relaxation; relaxing seldom to the same 
extent as the alkaline Ringer contracted. An m/64 to m/32 
NaCl produces a prolonged relaxation, whereas an m/32, and 
in some cases m/8 NaCl, proved indifferent. 
