EVOLUTION 987 



that the vital processes are quickened. The starveHng becomes young 

 again — surely a quaint biological justification of asceticism. Many 

 similar facts are given in Child's Senescence and Rejuvenescence 

 (Chicago, 1915). 



And what is true of nutrition is true of other factors in nurture; 

 they alter the punctuation of the life-cycle. A herring's Qgg in the 

 sea hatches in a little over a week ; put it in a refrigerator and the 

 development is slowed down so that the egg takes fifty days to 

 hatch. 



III. Without assuming that a peculiarity of the body, acquired 

 as the direct result of a peculiarity in nurture, can be as such or in 

 any representative degree entailed on the offspring, of which there 

 is insufficient evidence, we must recognise that nurture may be of 

 considerable importance to the race. The modification may give 

 the individual a life of conspicuous success or failure, which may 

 result in a subsequent increase or decrease in the numbers of the 

 type which it represents, thus obviously working for both good and 

 ill to the race. Vigour acquired by open-air exercise gives a man 

 resisting power against infection; it may keep bad constitutions 

 alive; it will also keep good constitutions from being gratuitously 

 weakened. Reduction of the likeUhood of infection will also work 

 both ways. 



It has often been pointed out that an individually acquired 

 modification may serve as a life-saving screen until an innate 

 variation with similar result has time to estabhsh itself. Thus 

 artificial immunity may be a useful temporary modification until 

 natural immunity arrives — if it does arrive. 



In the case of mammals the unborn offspring may be damaged 

 by the ill-nourished, over-strained, or poisoned state of the maternal 

 body. There is not transmission of acquired characters in the technical 

 sense, but there is ante-natal deterioration and arrestment of the 

 offspring as the result of abnormal nurture on the parent's part. 

 Some evidence exists which goes to show that deeply saturating 

 parental modifications, such as the results of poisoning, as by 

 syphilis, may affect the germ-cells. The influence very probably 

 affects the cytoplasm rather than the chromosomes. 



There is little likelihood that we are at an end of the question as 

 to the possible effect of modifications (nurture-effects) on inheri- 

 tance ; and a useful hint of the subtlety of the problem may be got 

 from a brief consideration of one of the most important British 

 investigations on the subject — Agar's study of a water-flea (Simo- 

 cephalus), a little crustacean with two valves. Under certain nutritive 

 conditions the crustaceans acquired a peculiar folding-back of their 

 shell-valves, doubtless as the result of altered metabolism. After the 

 eggs had appeared and grown in the ovary, the animals were 

 restored to normal conditions. In due time the eggs developed into 



