Neuter Insects and Lamarckism. 



A/fR. HERBERT SPENCER, defending Lamarkian views of 

 IVl heredity against Professor Weismann/ has to maintain that the 

 special structures and instincts of neuter insects were first developed 

 in fertile ancestors. He is driven to this assumption, because he holds 

 that complex evolution cannot occur without the aid of the inherited 

 effects of use and disuse ; and such use-inheritance is obviously 

 excluded in the case of neuter bees, ants, and termites, which cannot 

 transmit acquired characters to posterity. Of course, many of the 

 instincts and structures of neuter insects — such as those needed for 

 obtaining food, sheltering and feeding the larvae, and so forth — 

 were already present in the primitive queens or fertile females of 

 unsocial and semi-social stages. But in many other cases — and it is 

 these cases which more particularly demand our attention — it seems 

 hardly conceivable that the instincts and structures could ever have 

 been possessed by fertile ancestors. A few examples will illustrate 

 the improbability of Mr. Spencer's assumption. 



1. In some species of ants there is a caste of neuters possess- 

 ing " an enormously developed abdomen which secretes a sort of 

 honey, supplying the place of that excreted by the aphides, or the 

 domestic cattle, as they may be called, which our European ants 

 guard and imprison."^ Their abdomen is so distended with this 

 honey that they become almost unable to move. Is it credible that 

 parents were thus unfitted for the work of multiplication by becoming 

 living honey jars, or factories and storehouses for the general use of 

 the community or family ? Can we believe that queens or drones 

 first evolved so remarkable an unfitness for their special functions, 

 while still continuing the nuptial flights, and retaining the reproduc- 

 tive fertility which would be necessary for transmitting the effects of 

 use and disuse to posterity ? 



2. In the warrior caste of neuters among the termites — and in 

 this caste alone — the head and jaws are more than a third of the 

 total length of their possessors, and are " almost as big as the rest 

 of their bodies." These huge, heavy heads are carried with apparent 



^"A Rejoinder to Professor Weismann." Contemporary Rcvictv, December, 



1893- 



2 Origin of Species, p. 231. 



