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SCIENCE 



[N. S. Vol. LI. No. 1308 



significant, bearing on the question of the 

 greater likelihood of the first egg being a male 

 in " pure " species — a question that goes back 

 to Aristotle and has as often been denied as 

 aJRrmed. A table on page lYl (Table 170) 

 appears to indicate that this is the case in the 

 Streptopelia senegalensis where twelve males 

 came from the first egg, and only two females 

 came from the first egg, while only two males 

 came from the second egg and nine females 

 from the second egg. The evidence that has 

 been advanced in refutation of this relation is 

 due, the editor suggests, to the use of "mon- 

 grels, collectively known as domesticated 

 pigeons." More data must be obtained and 

 statistical treatment applied to settle this 

 question. The genetic evidence shows that 

 the female is heterozygous for the sex-chromo- 

 some, and if the method of disjunction of the 

 sex-chromosome in the egg is affected by the 

 conditions that prevail when the first egg is 

 set free from the ovary, we may possibly find 

 in this relation an excuse for such a result. 

 If this should turn out to be true, the cause 

 of the maleness of the generic hybrids must 

 be sought in some other direction. 



The chapter (XTV.) on Heredity contains 

 mainly the more general points of view 

 reached by Whitman in 1907. Coming at a 

 time when Mendel's discoveries had received 

 general notice and had been, even then, con- 

 firmed from many sources, the chapter con- 

 tains results of exceptional interest. The 

 groimds for Whitman's objection to any 

 theory resting on the assumption of unit- 

 characters is contained in the following strik- 

 ing paragraph: 



"Every theory founded upon the postulate 

 of unit-characters, or specific determinants 

 stored in the nucleus is necessarily committed 

 to some form of centrifugal distribution dur- 

 ing the course of development; and for each 

 element to be distributed it is necessary to as- 

 sume either that it is passively transported to 

 its destination or that it finds its own way 

 automatically. In either case it would be 

 nothing less than a miracle for a specific 

 pangen to reach a prescribed point in such a 

 complex mosaic field as the organism repre- 

 sents; and, for this to be fulfilled, not only at 



the predetermined point, but also just at the 

 moment for harmonious development with its 

 immediate neighbors, with symmetrical and 

 correlated groups, with inter- and intra-lock- 

 ing systems constituting a microcosmic whole, 

 incomparably more difficult to grasp than the 

 stellar universe — for all this to be fulfilled is 

 utterly beyond the boimds of scientific credi- 

 bility. To try to conceive of normal develop- 

 ment as thus prepunctuated in all its time 

 and space relations— as proceeding from ready- 

 made elemental characters, automatically dis- 

 tributing themselves or guided by entelechies 

 — is to indulge in ultra-scientific teleology." 

 The statement imputes apparently, to Men- 

 delism in so far as it deals with unit-factors 

 and unit-characters an implication from de 

 Vries's hypothesis of pangenesis; viz., the 

 migration from the nucleus of " organic 

 bodies " which multiply in the cytoplasm and 

 determine the fate of the cell. There is the 

 further implication that the migration is so 

 timed that it takes place at each critical place 

 in development. With Whitman's criticism 

 most students of heredity will agree, but it 

 should be noted, as I have pointed out above, 

 first that Mendel ism makes no such appeal, 

 second that the relation of specific materials 

 in the nucleus need not be supposed to have 

 any such time relations as here stated, and 

 third a careful reading of de Vries's " pan- 

 genesis " shows that he does little more than 

 make a passing reference to such an interpre- 

 tation and to-day, at any rate, it is not an es- 

 sential part of the doctrine of nuclear action. 

 Whitman's own view makes it evident that he 

 is not inclined to disregard the nucleus as one 

 of the elements in the " organization " that 

 supposedly has some action on " the cell as a 

 unit." Granting that differences may exist 

 in the nucleus of different species, different 

 end products are expected. The evidence that 

 such differences may be related to specific sub- 

 stances in the nucleus is no longer a specula- 

 tion but rests on the analytical evidence from 

 Mendelian heredity. In what way and at 

 what times the nuclear materials take part in 

 the determination of characters we do not 

 know. The essential point is that we are in 



