152 



SCIENCE. 



[N. S. Vol. XIX. No. 473. 



hair had been in the family since importation 

 [to Oregon(?)] and added: 'the growth and 

 quantity has increased with each generation.' 



It will be seen that the data are somewhat 

 inconclusive. Had the father as well as the 

 mother of Linus I. been long-haired (reces- 

 sive, according to Dr. Castle's hypothesis), 

 then we can understand the long hair of Linus 

 I. The latter was mated with a recessive ( ?) 

 mare (if 'remarkable growth of hair' may be 

 so interpreted) and produced Linus II. 



On the whole, it would seem more probable 

 that the long-haired property was dominant, 

 unless, indeed, Linus II. got no long-haired 

 progeny. The data are, as we see, insufficient 

 to decide the matter. 



The question of the Mendelian behavior of 

 animal mutations has long interested me and 

 I have collected some statistics bearing on the 

 subject. The records concerning polydactyl- 

 ism are, perhaps, the most complete and in- 

 structive. In the Jenaische Zeiischrift, X5II., 

 Fackenheim, 1888, has given a table that may 

 be thus summarized: Each letter n (normal) 

 or p (polydactyl) stands for a person," the 

 coefficient being used to indicate the number 

 of such persons in a family. 



only two cases. The majority of the p off- 

 spring should produce p and n in equal ntim- 

 bers in the second filial generation — we get 

 7 p and 12 n in generation III. and 5 p and 

 5 «, in generation IV. or 12 p and 17 n alto- 

 gether, which is a wide but not unlikely dis- 

 agreement from theory. Of the n children 

 mated with n consorts, theory would demand 

 that all should be n, since By^R gives only 

 B qualities. In the second filial generation 

 this happens in one family of seven children, 

 but does not happen in two families with a 

 total of 19 children in which 5 p's occur. The 

 total of the three families is 21 n and 5 p. 

 This is not Mendelism, but there is certainly 

 a marvelous prepotency of the normal quality. 

 In the third filial question from three ny^^n 

 families all of the 16 children are n. If we 

 had this generation only we should certainly 

 have a right to suspect that n is truly reces- 

 sive. 



Consider next the records of polydactyl cats 

 given by Poulton, 1883, in Nature. The 

 fathers are not laiown, but Poulton says it is 

 highly improbable that an abnormal female has 

 ever crossed with a likewise abnormal male. 



nXl 



Gen, 

 I. 



Ill I I I I I 



pn ny(n p'Xn nX™ mXp »X™ »Xp 



'' : • T I i I' i I 



II. 6)1 3p 4« 3p 7n Zn 2p 8n 2p £ 



On the assumption that polydactylism (p) 

 is dominant and the normal condition («,) is 

 recessive, any p of unknown ancestry may be 

 a (D -j-B). Then the offspring of the parents 

 BX(D + R) might give (DB) ■+ (BB) or 

 an equal proportion of p and n. There are 

 4 p and 4 n in the first filial generation; thus 

 agreeing with theory. Of the p offspring of 

 this first filial generation one third should be 

 pure D -{- D and should produce only poly- 

 dactyl children even with normal consorts. 

 This condition is not realized, for both of the 

 polydactyls of whose offspring we have a rec- 

 ord produced both n and p offspring; but this 

 is not surprising, considering that there are 



2p 



IV. 



PX? 

 I 



Ap 



This case is easily explained on Mendelian 

 principles, for assuming p to be dominant and 

 the mother in the first filial generation to have 

 {D -\- B) gametes, then there should be out of 

 10 offspring 5 p and 5 n; there are 6 p and 



