LITERATURE FOR 1916 ON ANTS AND MYRMECOPHILS 431 



were very active at the entrances to the nest and seemed to be 

 keeping the worker Amazons from making a sortie. 



Wheeler points cut that the raids here described took place 

 about two hours later than those recorded for the same and 

 other species in Colorado, Illinois, Pennsylvania, and New York. 

 He is inclined to believe that temperature and humidity in some 

 way regulate the time and day of the raid. The optimum 

 temperature for such raids he thinks is near 70 to 75 degrees F. 

 Wheeler states that future descriptions of Amazon expeditions 

 should be accompanied by accurate temperature, barometric 

 and humidity readings. The writer of this review hopes the 

 future investigators will take this suggestion of Wheeler's very 

 much to heart. Furthermore, the procedure which Wheeler 

 suggests should not be limited to slave raids of Amazon ants. 

 Every student of animal behavior should keep an accurate record 

 of the environmental conditions under which the behavior, which 

 he records, took place. This suggestion is particularly applic- 

 able to students and observers of insect behavior. Our ento- 

 mological journals are filled with new and interesting records of 

 observations on insect behavior but in practically no case has 

 the observer taken the time to record for us, the temperature, 

 the humidity, the rate of evaporation or any other of the envi- 

 ronmental factors that must have played such a large part in 

 determining the reactions which he records. One need not feel 

 that the recording of such factors makes him an advocate of 

 the mechanistic hypothesis, yet I am atraid that some feeling 

 of this kind does prevent certain entomologists from taking such 

 records seriously. Whether or not organisms are mechanisms 

 does not in the least alter the fact, which would seem to be 

 obvious, but which has also been demonstrated again and again 

 experimentally, namely, that animals in their natural environ- 

 ments are continually reacting to, and in many cases are largely 

 controlled by the stimuli, which impinge upon their receptors 

 from the surrounding environment. Experiment has also shown 

 quite clearly that temperature, light, and rate of evaporation 

 are especially important in the influence which they exert upon 

 the reactions of animals. No observer should consider his field 

 outfit complete until he has added to it a thermometer, an 

 atmorneter and a photometer. None of these instruments is 

 complicated or bulky and ail can be carried into the field without 



