NOTES 

 THE MATING OF LASIUS NIGER L. 



, C. H. TURNER 

 Sumner High School, St. Louis, Mo. 



It was three o'clock on the afternoon of September the seven- 

 teenth, 1913. For two days we had been having frequent 

 showers; even then, although the sun was shining brightly, 

 there were numerous clouds in the sky, any one of which, with- 

 out a moment's notice, might float before the sun. The temper- 

 ature was only 78 degrees Fahrenheit; but, compared with the 

 73 degrees of the afternoon of the sixteenth and with the 63 

 degrees of the afternoon of the fifteenth, it seemed quite warm. 

 The numerous nests of the ant Lasius Niger L., which had long 

 existed, unnoticed, beneath the pavements and in the vacant 

 lots of St. Louis, had suddenly been rendered conspicuous by 

 the restless myriads of gigantic virgin females, miniature males, 

 and small workers that were swarming from them and forming 

 agitated masses of ants about each entrance. 



On viewing this periodically repeated phenomenon one is 

 tempted to assume that the ants have suddenly become nega- 

 tively geotactic and positively phototactic; and this hypothesis 

 is strengthened by the fact that, on the evenings following such 

 an occasion, females of the species may be captured at the 

 street lights. It may have been a negative geotropism, it cer- 

 tainly was not a positive phototropism which urged the ants 

 from the nest; for the sunlight does not penetrate into the nests. 

 A prolonged and careful observation of the virgin females and 

 neuters of a nest situated at the foot of a large grape-vine re- 

 vealed conditions that do not harmonize with so simple an 

 explanation. If the behavior of these ants were wholly a nega- 

 tive geotropism, or a positive phototropism, or a combination 

 of both, then they should have climbed ever upward until the 

 tips of the twigs were reached; but, that is not the way they 

 behaved. Along the lower four feet of that vine the females 



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