The case of these mysterious communities of insects, composed largely of neuters which do the work of the community but do not reproduce their kind, was one of the difficulties in the way of Darwin’s theory of evolution which, he said, staggered him every time he reflected on it.[64] It is not surprising, therefore, that this difficulty came to be the battlefield, or a main position thereof, in a most interesting and illuminating controversy on Natural Selection _versus_ Lamarckism, waged between Mr. Herbert Spencer and Dr. Weismann in the years 1893-4.[65] Spencer considered the inheritance of acquired characteristics a factor in evolution of the very first importance; and so, indeed, from his point of view it is. “Either,” he declared, “there has been inheritance of acquired characteristics, or there has been no evolution.” Met by the case, among others, of the slave-making ants, his explanation is substantially as follows: It was not the workers (soldiers) which originally acquired military traits, but the queens, the fully developed females, which lost them. There was once, as every one admits, a time when all ants, bees, etc. were sexually mature. There were only males and females. At this stage, possibly, the Amazon ants were already predatory. It was _then_ that they may have acquired the military habits and structure, which they were then able to perpetuate by inheritance. How, then, did the queens lose these traits? “From the queens,” replies Spencer, “they have slowly disappeared by inheritance of the effects of disuse.” The obvious and unanswerable rejoinder made by Weismann and his followers was that Spencer had only shifted the difficulty to another ground—from the workers to the queens. If the queens (and drones) lost the military characteristics by disuse, how do they come to transmit them unimpaired to the workers? It is the very essence of Lamarckism that whatever modifications are produced by use or by disuse shall be transmissible by inheritance.