328 NATURAL SCIENCE. Mav, 



ascribed to a fundamental property of protoplasm, which it is not 

 the business of Lamarckians or evolutionists of any other school to 

 explain. But, apart from this, let us consider how far back in the 

 phylogeny of vertebrates we must go to find the origin of a circulatory 

 system ; and consider that, from this point onwards, if changes in 

 the locomotor system are due to the use and disuse of various parts 

 of this system, and are inherited, then there is practically no limit to 

 the variety and perfection of the adaptations in the locomotor system 

 which can be explained by the Lamarckian factor. If selection 

 produced in the remote ancestor the circulation and the structural 

 arrangement by which muscle (and, of course, bone and other con- 

 nective tissues and nerves) received increased supplies of blood when 

 exercised, then it would require to produce nothing else to account for 

 such adaptations as the neck of the giraffe, the various arrangements 

 of the toes and limbs in ungulates, the peculiarities of the legs and 

 skeleton in man which enable him to maintain the erect attitude, the 

 form of the pectoral muscles and sternum in flying birds, the absence 

 of the keel on the sternum in ostriches, the peculiarities of the 

 tongue and hyoid bone in woodpeckers, of the beak in crossbills, and 

 thousands of other mechanisms, all consisting in adjustments of 

 muscle, bone, and nerve. 



Professor Brooks next proceeds to argue that organs are only 

 improved by normal or natural use, and that only with this limitation 

 is use beneficial. " The ways to use a muscle are few, while the 

 ways to abuse it are innumerable, and the inheritance of all the effects 

 of the conditions of life must lead, not to ' cumulative adaptation,' but 

 to cumulative destruction " ; but no Lamarckian supposes that the 

 action of the environment is necessarily beneficial. It would be 

 interesting to know what meaning Professor Brooks attaches to the 

 words " the ways to abuse a muscle are innumerable." To myself 

 they are unintelligible. A muscle can be used, disused, or over- 

 exerted — in fact, there is only one way to use it, and that is to con- 

 tract it. Excessive strain which does not cause development and 

 increase of the muscle must lead to injury and ultimately to the 

 death of the organism. Disuse leads to degeneration. Degeneration 

 is not necessarily beneficial, but it is included in the conception of 

 adaptation, and it may be beneficial in relation to the adaptation of 

 the whole organism to a new mode of life. The case of a herd of 

 antelopes hunted by carnivores will illustrate the different points of 

 view of the Lamarckian and the selectionist. Certain individuals, we 

 may suppose, are caught and killed, others may escape and die of 

 fatigue or an over-strained heart, while the rest escape and recover 

 their strength. The fact that some are killed is in no way incon- 

 sistent with the fact that the survivors are improved with respect to 

 the muscles and bones on which their running powers depend. It 

 may even be that the persecution is so great that the constitutions of 

 the whole herd are injured, their progeny are not sound, or are 



