38 THE entomologist's record. 



At the same time the phenomenon of reversion is explained by sup- 

 posing that, whilst many, or most of the ids, undergo change, yet some 

 of the " ids "will remain unchanged, and the occasional development 

 of an unchanged " id "produces a reversion. 



The Professor then asks " if in the germ-plasm of the bee there is 

 only one primary constituent capable of developing into a queen 

 under the influence of rich food, and into a worker when poorly 

 nourished, how could we explain the fact that in the latter case not 

 only does degeneration of individual parts occur, but also a different 

 and stronger development of other parts '? " He points out that the 

 stimulus of poverty of food brings about degeneration of the ovaries, 

 the receptaculum, and the wings, and frequently a reduction of the 

 entire bulk of the body on the one hand ; and on the other, increase 

 and higher differentiation of individual parts, such as the brain in 

 worker ants, and the head and the jaws in soldiers. We have yet to learn 

 the excess of brain development in the worker over the queen ant, and 

 its dependence on quantity of food, whilst the researches of Grassi 

 show that the extra development of soldiers above workers is also 

 brought about by food. The difticulties of Weismann's explanations 

 lie in the fact, that all these modifications of the insect are possible 

 after the larva has existed some time as a larva — i.e., as an indepen- 

 dent organism, capable of being acted upon by its own environment — 

 and since the quantity of food given determines the amount of structure 

 built, and a small quantity of food ends in the production of certain 

 ill-developed structures, whilst a larger quantity of food produces the 

 same structures in a more perfect and well-developed form, it appears to 

 be rather far fetched to say that these variations — even the frequently 

 striking small size of the workers — do not originate owing to the "direct 

 action of poor food." It is ridiculous to say that the poverty of food 

 is only the stimulus by means of which these ill-developed structures 

 are produced, whilst the richness of food is only the stimulus by means 

 of which the well-developed structures are produced, when a supply of 

 rich food will produce them if the larva gets it when quite young ; it 

 seems to me only a matter of common logic that if the larger quantity 

 of rich food is wanted for full development, that the smaller quantity 

 of poor food cannot produce full development, and cannot supply even 

 the crude material to build up the more complex structures. The 

 latter cannot be built up it is clear, because the worker-larva does not 

 get the necessary food to do it ; give the worker more food, raise its 

 temperature — in other words, produce in the insect more energy — and 

 the worker becomes a queen, or reaches some intermediate stage on the 

 way to doing so, in proportion to the increase of energy developed. 

 " Should we attempt to make dwarfs of any insect by starvation 

 during the course of development, we should at most get a reduction 

 to about half the normal size," the Professor says, and I would add to 

 to this, "in one generation." This result the Professor obtained in a few 

 days with 3Insra, and Ave can get a similar result with many moths in a 

 few weeks. What would be the result of continuing this for ages ? Many 

 insects we should exterminate, others would adapt themselves to the 

 altered conditions. Many dwarf races of common insects do maintain 

 a precarious existence on the bleak hill-sides, &c., where the food is 

 sparse, Avhilst their larger relatives in other localities revel in plenty. 

 Natural selection has adapted them in large part to their surroundings, 



