334 



NATURE 



[August 2, 1900 



to a near ancestor we need a broader basis of fact than we have 

 at present before we can formulate any law. The recorded 

 cases show that many phenomena are labelled reversions on the 

 flimsiest evidence. Thus the occurrence of a Cyclopean human 

 monster with a median eye has been called a reversion to the 

 sea-squirt, and gout has been called a reversion to the reptilian 

 condition of liver and kidneys. Often there is not the slightest 

 attempt to discriminate between true reversion {i.e. the re- 

 expression of latent ancestral characters) and the phenomena of 

 arrested development, or of abnormalities which have been 

 induced from without. Often, too, there has been no scruple in 

 naming or inventing the ancestor to whom the reversion is 

 supposed to occur, although evidence of the pedigree is awanting ; 

 and the vicious circle is not unknown of arguing to the supposed 

 ancestor from the supposed reversion, and then justifying the 

 term reversion from its resemblance to the supposed ancestor. 

 Little allowance has been made for coincidence, and the postulate 

 of characters remaining latent for millions of years is made as 

 glibly as if it were just as conceivable as a throw-back to a 

 great-grandfather. 



There seems no way out of the theory that characters may lie 

 latent for a generation or for generations, or in other words that 

 certain potentialities or initiatives which form part of the 

 heritage may remain unexpressed for lack of the appropriate 

 liberating stimulus, or for other reasons, or may have their 

 normal expression disguised. But it does not follow that the 

 reappearance of an ancestral character not seen in the parents is 

 necessarily due to the reassertion of latent elements in the 

 inheritance. It may be a case of ordinary regression ; it may be 

 a case of arrested development ; it may be an extreme variation 

 whose resemblance to an ancestral characteristic is a coincidence ; 

 it may be an individually acquired modification, reproduced 

 apart from inheritance, by a recurrence of suitable external condi- 

 tions, and so on. What are called reversions are probably in 

 many cases misinterpretations. 



V. Galton's Law. 



The most important general conclusion which has yet been 

 reached in regard to inheritance is formulated in Galton's Law. 

 Mr. Gallon was led to it by his studies on the inheritance of 

 human qualities, and more particularly by a series of studies on 

 Basset hounds. It is one of those general conclusions which 

 have been reached statistically, and I must refer for the evidence 

 and also for its strictest formulation to the revised edition of Mr. 

 Pearson's " Grammar of Science." ^ 



As we have seen, it is useful to speak of a heritage as dual, 

 half derived from the father and half from the mother. But the 

 heritable material handed on from each parent was also dual, 

 being derived from the grandparents. And so on, backwards. 

 We thus reach the idea that a heritage is not merely dual, but 

 in a deeper sense multiple. 



To appreciate the possible complexity of our mosaic inheri- 

 tance we must recall the number of our ancestors. We have 

 two parents, four grandparents, eight great-grandparents, about 

 sixteen great-great-grandparents, and so on. But as we go back- 

 wards the theoretical number far exceeds the reality ; a reduc- 

 tion in the number of ancestors is brought about by inter-mar- 

 riage, as this table (from Lorenz) in reference to Kaiser Wilhelm 

 II. clearly shows. 



Generations. I. II. III. IV. V. VI. VII. VIII. IX. X. XI XII 



(i) Theoreticall o ^ ^ „ 



Number. / ^ 4 ° i6 32 64 128 256 512 1024 2048 4096 

 (2) Actual \ 



number 

 known. ) 



(3) Inadequate-) 



ly known. / 



(4) Probable \ 



total. / 



24 44 74 



162 



225 27s 



256 342 533 



According to Galton's Law, " the two parents between them 

 contribute on the average one-half of each inherited faculty, each 

 of them contributing one-quarter of it. The four grandparents 

 contribute between them one-quarter, or each of them one- 

 sixteenth ; and so on, the sum of the series, ^ + i + i -I- yV + &c. , 

 being equal to i, as it should be. It is a property of this infinite 

 series that each term is equal to the sum of all those that follow • 

 thus i= K J + iV -t- &c. ; i = 1 + ^V + &c., and so on. The pre- 

 potencies or subpotencies of particular ancestors, in any given 

 pedigree, are eliminated by a law that deals only with average 

 1 Reference should, however, be made to Mr. Pearson's recent paper 

 froe. Aoy. :>oc., Ixvi. 1900, pp. 140-164) on the law of reversion. 



NO. 1605, ^'OL. 62] 



contributions, and the varying prepotencies of sex in respect to 

 different qualities are also presumably eliminated." 



The aim of this lectiire has been to present in brief compass a 

 statement of the leading facts of inheritance, which should be 

 clear in the minds of all. Nothing has been said in regard to 

 the transmissibility of acquired characters, for this cannot be 

 ranked at present as an established fact, and some other doubtful 

 points have been left unmentioned. The study of inheritance 

 leaves a fatalistic — almost paralysing — impression on many 

 minds, especially perhaps if it be believed that the acquired 

 results of experience and education — of "nurture," in short, 

 cannot be entailed upon the offspring. To some extent this 

 fatalistic impression is justified, but it is well that it should rest 

 upon a sound basis of fact and not on exaggerations. In a sense 

 we can never get away from our inheritance. As Heine said 

 half bitterly, half laughingly, "A man should be very careful 

 in the selection of his parents." On the other hand, although 

 the human organism changes slowly in its heritable organisation, 

 it is very modifiable individually, and " nature " can be bettered 

 by " nurture." If there is little scientific warrant for our being 

 other than sceptical at present as to the inheritance of acquired 

 characters, this scepticism lends greater importance than ever, 

 on the one hand, to a good '* nature," to secure which for off- 

 spring is part of the problem of careful mating ; and, on the 

 other hand, to a good "nurture," to secure which for our chil- 

 dren and children's children is one of the most obvious of duties, 

 the hopefulness of the task resting upon the fact that, unlike the 

 beasts that perish, man has a lasting external heritage, capable 

 of endless modification for the better. 



UN/ VERS! TY AND ED UCA TIONA L 

 INTELLIGENCE. 



Mr. a. Rendle Short, of University College, Bristol, has 

 been awarded the gold medal and exhibition in physiology, the 

 gold medal and exhibition in materia medi'ca, and first-class 

 honours in anatomy, upon the results of the recent Intermediate 

 M.B. examination of the University of London. The exhibi- 

 tions in physiology and materia medica are of the value of 80/. 

 and 60/. 



A DISCUSSION on the teaching of geography will be held at 

 Cambridge on Friday, August 24, under the auspices of the 

 Geographical Association, and in connection with the Summer 

 Meeting. Prof. W. M. Davis, of Harvard University, will 

 occupy the chair, and among the subjects to be brought before 

 the Association are class excursions, map drawing, the use of the 

 globe, geography in the grammar school, and possibilities and 

 limitations of geography in a day school. There are several 

 exhibits of interest to teachers of geography in the education 

 exhibition, arranged in connection with the Summer Meeting. , 



Lord Bute has offered the University of St. Andrews a sum 

 of 20,000/., to be held as a fund for endowing a chair of 

 anatomy, upon the following conditions : — (i) That the said sum 

 of 20,000/. shall be paid to the University not later than ten 

 years hence. The exact date cannot be specified, as it will 

 depend upon completion of certain works at Cardiff. Interest 

 at 3 per cent, will be payable to the University from the time 

 of the appointment of the first professor until they receive the 

 principal sum ; (2) that the first presentation to the chair shall 

 be in favour of Mr. Musgrove, the present holder of the lecture- 

 ship in anatomy in St. Andrews ; (3) that the lectures shall be 

 given exclusively in St. Andrews ; (4) that the course shall meet 

 the requirements of the two first Anni Medici ; and (5) that 

 before the beginning of the University session, 1 901 -1902, the 

 approval of the Universities Committee of the Privy Council to 

 the establishment of the chair under the foregoing conditions be 

 obtained, and that the approval of Lord Bute or his representa- 

 tives be obtained to any further conditions embodied in the 

 ordinance instituting the chair. 



The relations between scientific work and industrial progress 

 have been so often described in these columns that there is little 

 new to be said upon the subject. But though readers of Nature 

 may be familiar with many instances of the close connection 

 between science and industry, it will be a long time before the 

 knowledge filters down to the general public and starts a reaction 

 in commercial and manufacturing circles. Every man of science 

 who takes advantage of an opportunity to impress the value of 

 scientific observation and research upon the minds of citizens, 



