282 SELIG HECHT 
muslin broke the foree of the current of water which flowed from 
the tip of the pipet by dividing it into many minute streams. 
The liquid still came out in an apparently coherent mass, but its 
velocity and force were much reduced. One cubic centimeter 
of ordinary seawater from such a muffled pipet directed into the 
oral siphon left the animals undisturbed. 
The results obtained by the use of this method were gratify- 
ingly uniform. At the normal summer temperature of 26.0° 
to 27.0°C. the discharge of 1 ce. of seawater at 32.0° within five 
millimeters of the oral siphon produced a reaction in most cases. 
Seawater at 35° and at higher temperatures acted as undoubted 
thermal stimuli. The reactions were always of the crossed 
variety, which has already been described. For temperatures 
below that of the room, the reactions were analogous. Seawater 
at 20.0° very frequently acted as a stimulus. Temperatures 
below 20.0° were practically invariable in their stimulating effects. 
From these facts it is clear that over a range of 12 degrees A. 
atra is insensitive to temperature changes. Undoubtedly this 
recorded range is greater than the actual one, because of the 
dilution and consequent change of temperature of the stream of 
warm or cold water. A rough approximation of the tempera- 
tures to which the animal was actually exposed is furnished by 
substituting a small thermometer in its place and directing the 
water on the bulb. The temperatures recorded by the thermom- 
eter in one such experiment are given in the following table 
(table 3). It must, however, be remembered that the case of a 
sense organ and of a thermometer are only roughly comparable, 
because of the much larger volume of substance which has to be 
heated in the thermometer bulb. The actual temperature to 
TABLE 3 
TEMPERATURE IN DISH SSeeeeee Gee | THERMOMETER READING 
2728" 41.0° 30.2° 
28.0° 46 .0° SEIS 
28 .0° 50.0° 32.02 
28.0° 54.0° . 32.5" 
28 .0° 67.0° 35.0° 
28 .0° 76 .0° 37 .0° 
