THE RELATIVE POSITION OF THE MAXIMA CON- 
TRACTIONS OF THE AMPHIBIAN MUSCLE 
WHEN SUBJECTED TO VARIOUS 
RANGES IN TEMPERATURE 
RALPH. L. PARKER 
In the regular laboratory work in muscle-nerve physiology, it 
was noted that records obtained by subjecting frog muscles to 
various ranges of temperature did not exactly agree as to positions 
of maxima contractions with statements found in the texts, 
especially that of Howell.^ At the suggestion of Dr. F. M. Bald- 
win a fairly large series of experiments has been carried out to 
determine the relative positions of maxima contractions of the gas- 
trocnemius muscle of the frog under varying temperature condi- 
tions, and to compare the results thus obtained with those of other 
investigators. Two of the muscles died from being subjected to 
low temperatures so there were only twenty complete records. 
Many investigators have worked with this particular muscle and 
observed the effect of heat in other ways ; duration of contraction 
at different ranges of temperature ; the cause of heat rigor 
periods of irritability;® fatal maximum temperature at which a 
frog or exsected muscle will survive Howell, however, is 
the only one so far as I can find in the literature to make any 
statement concerning the position of the maxima contractions. 
Fall or winter frogs of the species Rana pipiens were used and 
were obtained from a supply house in Chicago. Apparatus used 
was a muscle-lever, muscle-warmer with thermometer, bunsen 
burner, container for water bath, induction coil and key, and a 
rotary kymograph. All except the water container were of the 
Harvard type of instruments. The water container was of con- 
venient size and made of galvanized iron. The exsected muscles 
were suspended within the muscle-warmer by means of a short 
wire terminating in hooks at each end. The opposite end from 
the muscle was attached to a wire hook on the short arm of the 
muscle-lever. The thermometer was placed in the muscle-warmer 
next to the muscle. The muscle-warmer was immersed in the 
solution within the container and then heated or cooled as was 
desired. A single stimulus was used of sub-maximal strength. 
