INSECT SOCIETIES — LAMEERE. 517 



of the female or each year, when, as among the domestic bee and 

 the ants, its existence is much more prolonged, which explains how 

 it comes about that the neuters of the hymenoptera are exclusively 

 females : Under the conditions in which neuters are produced, their 

 mother is in a period when she lays only fertilized eggs. 



V. 



Let us follow the study of the neuters among all of the social 

 insects. We note that they differ from normal individuals by certain 

 characteristics peculiar to each of the categories to which they belong 

 and by various features which are common to all. Let us examine 

 these. 



The neuters are sterile, but this sterility is relative. At birth their 

 genital organs are in general simply arrested in development; it is 

 rarely that they are completely atrophied, as in the ant Tetramorium 

 caespitum. This castration is the result of insufficient nourishment 

 in the larval state. It is followed, as M. Paul Marchal has observed, 

 by a nutrimental castration, the neuter passing to the young the 

 greatest part of the nourishment which it can gather, and keeping 

 for itself only a portion too scant to develop its genital organs. 

 M. Paul Marchal has proved that worker wasps, when restrained from 

 their duties as nurse and abundantly nourished, begin to lay eggs. 

 In this way can be explained why the neuters, as well among the 

 wasps as among the bees and the ants, can under special conditions of 

 nourishment be fertile and lay eggs which always produce males, 

 since these neuters never pair. It is also by means of special nourish- 

 ment that the termites can transform from workers, and even from 

 soldiers, to supplemental kings or queens, not resembling completely, 

 however, the true king or queen, in case of the death of these. 



The neuters, as they are, differ further from normal individuals 

 through a partial suppression of their instincts. The desire to mate 

 is absent among them, which is due, no doubt, to the condition of 

 their genital organs. Having no offspring except in exceptional 

 cases, they gratify their instincts as builders and as nurses, which 

 remain intact, to the profit of their brothers, and they do not emi- 

 grate, probably in accordance with the law of least effort. They 

 profit from the work begun by their parents or b} r their mother. 



VI. 



The morphological characteristics which greatly differentiate the 

 neuters from normal individuals, or the new instincts which the 

 neuters present, are much more difficult to explain. We are con- 

 fronted by various theories, the biologists having tried to apply to 

 insect societies the explanations which they have adopted to interpret 



