LITERARY NOTICES. 



275 



when the processes are matured. By it is 

 deduced an equation suggesting a theory of 

 descent, to be applied in the subsequent in- 

 vestigations. The investigations were made 

 by the aid of experiments on sweet peas (the 

 sizes of the peas of a crop), and on moths 

 bred for the purpose, and of about a hun- 

 dred and fifty family records. The records, 

 of course, include facts relating to a vastly 

 larger number of persons. The chief sub- 

 jects to which they relate are stature, eye- 

 color, temper, the artistic faculty, some 

 forms of disease, marriage selection, and fer- 

 tility. The item of stature offers many ad- 

 vantages in the study — from the ease and 

 frequency with which it may be measured 

 and its practical constancy during many 

 years, from the fact that it is not a simple 

 element, but is the sum of the accumulated 

 lengths or thicknesses of many bodily ele- 

 ments, and because its discussion need not be 

 entangled with considerations of marriage 

 selection, and its variability is normal. To 

 the inheritance of stature each mid-parent 

 (median between the two parents) contrib- 

 utes an influence marked as one half, each 

 individual parent one quarter, and each indi- 

 vidual grandparent one • sixteenth. A like 

 hereditary relation is found to exist between 

 the man and his ancestors in the matter of 

 eye-sight. In point of the artistic faculty, 

 highly artistic people intermarry, while mod- 

 erately artistic people do not so usually, be- 

 cause, "A man of highly artistic tempera- 

 ment must look on those who are deficient 

 in it as barbarians; he would continually 

 crave for a sympathy and response that such 

 persons are incapable of giving. On the other 

 hand, every quiet unmusical man must shrink 

 a little from the idea of wedding himself to a 

 grand piano in constant action, with its vocal 

 and peculiar social accompaniments ; but he 

 might anticipate great pleasure in having a 

 wife of a moderately artistic temperament, 

 who would give color and variety to his pro- 

 saic life. On the other hand, a sensitive and 

 imaginative wife would be conscious of need- 

 ing the aid of a husband who had enough 

 plain common sense to restrain her too en- 

 thusiastic and frequently foolish projects." 

 And vice versa. Of the problem as related 

 to disease, the author observes : " The vital 

 statistics of a population are those of a vast 

 army marching rank behind rank, across the 



treacherous table-land of life. Some of its 

 members drop out of sight at every step, 

 and a new rank is ever rising to take the 

 place vacated by the rank that preceded it, 

 and which has already moved on. The pop- 

 ulation retains its peculiarities, although the 

 elements of which it is composed are never 

 stationary; neither are the same individuals 

 present at any two successive epochs. In 

 these respects a population may be compared 

 to a cloud that seems to repose in calm upon 

 a mountain plateau while a gale of wind is 

 blowing over it. The outline of the cloud 

 remains unchanged, although its elements 

 are in violent movement and in a condition 

 of perpetual destruction and renewal. . . . 

 Both in the cloud and in the population 

 there are continual supply and in-rush of 

 new individuals from the unseen; they re- 

 main awhile as visible objects and then 

 disappear. The cloud and the population 

 are composed of elements that resemble 

 each other in the brevity of their existence, 

 while the general features of the cloud and of 

 the population are alike in that they abide." 

 One of the striking facts disclosed in the 

 classification of the diseases of each family 

 is their great intermixture. We know very 

 little about the effects of such mixture, how 

 far they are mutually exclusive, and how far 

 they blend; or how far, when they blend, 

 they change into a third form. Owing to 

 the habit of free intermarriage, no person 

 can be exempt from the inheritance of a va- 

 riety of diseases, or of special tendencies to 

 them. While death by mere old age and 

 failure of vital powers appears common, it is 

 not found, as a rule, that the children of per- 

 sons who die of old age have any marked 

 immunity from specific diseases. Applying 

 the inquiry to consumption, the law of hered- 

 ity found to govern the other faculties exam- 

 ined appears to govern that of liability to 

 this disease also, although the constants of 

 the formula differ slightly. It is not pos- 

 sible that more than one half of the varie- 

 ties and number of each of the parental ele- 

 ments, latent or personal, can, on the average, 

 subsist in the offspring; for a calculation 

 based upon the supposition that they can all 

 be conveyed would soon lead into absurdi- 

 ties. But if the personal and latent ele- 

 ments are transmitted on the average in 

 equal numbers, it is difficult to suppose that 



