Januaey 23, 1920] 



SCIENCE 



77 



the situation rightly no one would be bold 

 enough to claim any such time relations of 

 pangen migration nor does the theory of 

 nuclear influence call for such a hypothesis in 

 any sense. It is ony necessary that nuclear 

 influence should in some way affect the 

 chemical changes that go on in the surround- 

 ing cell to cover completely the situation. No 

 time relation is expected or called for, and 

 who to-day will deny, in the face of extensive 

 evidence, that the nucleus does have an im- 

 portant influence on the cell? With this 

 understanding one can agree cordially with 

 Whitman's concluding thrust : " The doctrine 

 of germs laden with independent unit-char- 

 acters, or pangens, each predestined, so to 

 speak, to flower in its own place and time 

 strikes me as teleological mythology, fine spun, 

 to the verge of absurdity. We have not yet 

 fathomed primordial organization, but it is 

 safe to assume that the germ sets out with a 

 biophysical constitution of a given specific 

 type, within which metabolic, generative and 

 differentiating processes under normal condi- 

 tions run on in a self-regulating way." 



The title of Volume II. epitomizes its con- 

 tents, " Inheritance, Fertility and the Domi- 

 nance of Sex and Color in Hybrids of Wild 

 Species of Pigeons." Seven manuscripts of 

 less than one hundred pages, nearly 2,000 

 pages of breeding records, and two hundred 

 illustrations comprised the original material 

 of this volume of two hundred twenty-three 

 pages. Only a few chapters, viz., I. (1904- 

 05), XII. (189Y), XVI. (1898), and XVH. 

 (1906) were left complete. The remaining 

 chapters (containing fragments and sections 

 by Whitman, and his breeding records) con- 

 sist in large part of analyses and discussions 

 by the editor based on Whitman's data to 

 which have been added many of the later ob- 

 servations and views of the editor. This work 

 of elucidation and summarization has been 

 well done, making the text readable, and 

 guiding the reader through a maze of not com- 

 pleted and intricate data. 



One of the outstanding results of the hy- 

 bridization work, which constitutes the bulk 

 of this volume, is that offspring produced by 

 crossing species of generic or family rank are 



males. This fact is in conformity with re- 

 sults obtained in other species of birds (see 

 Guyer). The result is however complicated, 

 according to the editor, by a second result, 

 viz., " that, in many crosses of very distinct 

 genera and species, fertility (developmental 

 power) is shown to be highest in the spring 

 and lowest in the autumn, and that male off- 

 spring predominate in the season of highest 

 fertility, while females largely predominate in 

 the season of lowest fertility." Several pages 

 attempting to explain the apparent contra- 

 diction follow this statement, but since " it 

 may be emphasized that Professor Whitman 

 was by no means inclined to dogmatize as to 

 the interpretation of this sex series," the sub- 

 ject need not be fvu-ther discussed here. 



In certain crosses between checkered and 

 barred domesticated races the results show 

 that checkered birds may throw some barred 

 offspring. That the two may differ by a 

 single factor difference may seem probable, 

 especially in the light of other evidence (Bon- 

 hote and Smally, Staples-Browne) not re- 

 ferred to in the text. The relation is men- 

 tioned here because it elucidates a point not 

 fully understood by opponents of Mendelian 

 interpretation, viz., that such a relation is 

 not claimed by most Mendelians as showing 

 necessarily that the barred character must 

 have arisen by a single mutation, although it 

 may have done so. There may have been, as 

 Whitman thinks, a long line of more graded 

 intermediate steps between the two; still the 

 barred and the checkered types might be differ- 

 entiated to-day by a single factor difference 

 provided both contained all other genes in 

 common. In other words the modem check- 

 ered and barred birds, as compared with the 

 old checkered type, would be supposed to 

 carry an entire series of gradually acquired 

 factors, and the checkered birds one further 

 factor. Thus one change in the complex that 

 gave the barred type is supposed to have 

 sufficed to suppress all of the new stages. 

 The two checkered birds would differ then in 

 the entire series of gradually acquired factors, 

 and also in the single final factor that caused 

 the apparent badt-throw. There are also 

 records, some of them too fragmentary to be 



