634 



SCIENCE 



[N. S. Vol. LIV. No. 1408. 



things not already necessarily implied in the 

 past. " The outstanding fact about organic 

 evolution is the increasing dominance of 

 Mind." " Unless we have quite misunder- 

 stood evolution it implies an emergence of 

 novelties. It is like original thinking." In 

 it there is something like the joyous play of 

 the organism at self expression. " It may 

 be well for us, on our own behalf and for our 

 children to ask whether we are making what 

 we might of the well-springs of joy in the 

 world; and whether we have begun to know 

 what we ought to know regarding the Biology 

 or the Psycho-biology of Joy." 



Perhaps the most remarkable single matter 

 in these lectures is the suggestion of a sort 

 of cell-intelligence, particularly in the germ- 

 cells. " Just as an intact organism from the 

 Amoeba to the Elephant tries experiments, so 

 the germ-cell, which is no ordinary cell, but 

 an implicit organism, a condensed individ- 

 uality, may make experiments in self-expres- 

 sion, which we call variations or mutations. 

 Such, at least, is our present view of a great 

 mystery." " The position we are suggesting 

 is that the larger mutations, the big novelties, 

 are expressions of the whole organism in its 

 germ-cell phase of being, comparable to ex- 

 periments in practical life, solutions of prob- 

 lems in intellectual life, or creations in artis- 

 tic life." " The germ-cell is the blind artist 

 whose many inventions are expressed, em- 

 bodied, and exercised in the developed organ- 

 ism, the seeing artist who, beholding the work 

 of the germ-cell, either pronounces it ... to 

 be good or . . . curses it effectively by sink- 

 ing with it into extinction." 



E. D. Carmichael 

 XJniveesitt op Illinois 



SPECIAL ARTICLES 



MORE LINKED GENES IN RABBITS 



In Science for August 13, 1920, I pre- 

 sented evidence indicating the existence of 

 linkage between the genes for English spot- 

 ting and dilute pigmentation in rabbits. The 

 evidence consisted of a group of 83 young 

 produced in matings of a male heterozygous 

 for both characters, mated with doubly re- 



cessive females. Such matings are expected 

 to produce equal numbers of individuals of 

 four color classes, if no linkage exists. Con- 

 sistently, in his successive litters of offspring, 

 this male sired more young in the non-cross- 

 over classes than in the cross-over classes, 

 which result indicated linkage of strength 

 23 on a scale of 100, the cross-over percen- 

 tage being 38.5. 



A second heterozygous male has since been 

 tested, in similar matings with doubly re- 

 cessive females, for the occurrence of linkage 

 between the same pair of characters as seemed 

 to be linked in the gametes of the first male, 

 but shows no linkage with as much consist- 

 ency as the first male showed linkage. The 

 totals for the first male were 32 cross-over; 

 51 non-cross-over gametes; for the second 

 male they are 75 : 76, as near equality as 

 possible. The question now arises. Were the 

 results given by the first male statistically 

 significant? The cross-over percentage cal- 

 culated as 38.5 has a probable error of 3.6 

 per cent. Hence the departure from 50 per 

 cent, cross-overs (which would indicate no 

 linkage) slightly exceeds three times the prob- 

 able error, a result which would ordinarily 

 be considered significant. Unfortunately no 

 further experimental tests of this animal can 

 now be made as he is no longer living. There 

 can be no doubt about the negative result 

 given by the second male. We are now con- 

 fronted by this dilemma. Either the result 

 given by the first male was not significant, 

 or we may have in the same strain oi rabbits 

 two individuals, in one of which two char- 

 acters show linkage, while in the other they 

 do not show linkage. This latter alternative 

 seems improbable, yet it can not be regarded 

 as impossible on the chromosome hypothesis. 

 Gates and Rees ^ in discussing the pollen de- 

 velopment of Lactuca sativa state that the 

 number of chromosome pairs in the species 

 is nine but that 



Occasionally in diakinesis only eight cliromosome 

 bivalents were present, and frequently there were 

 only seven or eight bodies present on the hetero- 

 typic spindle. This was found to be due to a tem- 



1 Annals of Botany, 35, 1921, p. 394. 



