May 27, 1920] 



NATURE 



405 



inadequate for its needs. It would be out of place 

 for me to enlarge on the advantages to be expected 

 from securing- the concentration of the headquarters 

 of the University and its two incorporated colleges 

 on a single site, in a quiet residential quarter close 

 to our greatest National Library and Museum, and 

 capable of expansion in the future as the need may 

 arise. The merits of this site, as of other alternative 

 sites which have from time to time been suggested, 

 have, I know, been the subject of much discussion 

 by the friends of university education in London, 

 and I have no doubt that' the University is fully 

 apprised of the considerations which need to be 

 weighed. I have no desire to persuade the University 

 against its will. No one recognises more fully than 

 I do the right of universities to control their own 

 destinies and shape their own policies. The responsi- 

 bility for accepting or declining the Government's 

 offer must rest wholly with the University, which 

 alone is in a position to estimate how far the proposal 

 I communicate to you is likely to advance what it 

 conceives to be its true interests. The view of the 

 Government is, I think, sufficiently indicated by their 

 willingness to provide for the University a site of 

 great value in the heart of London, at a' time when 

 there is "no temptation to incur expenditure upon any 

 but objects of first-rate urgency and importance. 



"It had at one time been my hope that the Govern- 

 ment would be able to offer not only the site of which 

 I have spoken, but also the buildings for the new 

 University headquarters : the Government have, how- 

 ever, reluctantly come to the conclusion that, while 

 they are prepared to make such provision as will 

 secure the University from loss in respect of main- 

 tenance charges on the new L'niversity headquarters, 

 the state of the national finances did not justify their 

 undertaking to provide the cost of the buildings' them- 

 selves from public funds. They feel that in a matter 

 in which the honour and dignity of the City of London 

 are so nearly concerned, the University can look with 

 confidence to the generosity and public spirit which 

 have always marked the citizens of London : it can 

 do this with the greater assurance that recent years 

 have shown an increasing readiness upon the part of 

 the great business community to respond to appeals 

 for L'niversity purposes. 



" I am aware that a matter of such importance to 

 the L'^'niversity needs to be fully discussed, and that I 

 cannot fairly expect an immediate answer to the 

 Government's offer. At the same time the University 

 will understand that the Government are naturally 

 anxious to know as soon as possible whether their 

 offer will be accepted or not, since, if it should be 

 declined, they propose to make early use of the site 

 for other purposes. I have, therefore, to ask that 

 the University's answer may not be unduly delayed." 



The matter was referred to a special committee 

 for consideration and report as speedily as possible. 



N' 



Genetic Studies of Drosophila.^ 



O single animal has provided such a rich field for 

 discovery in genetics as the little fruit-flv Droso- 

 phila (usually known as D. ampelophila. but now 

 called D. melanogaster), and in this large and hand- 

 somely illustrated volume Prof. Morgan and his col- 

 laborators bring together the results of some of their 



' Contributions to the Genetics of Drotofili'lamelanogasttr. I. "The 

 Origin of Gynandromorphs." By T. H. Morgan and C. B. Hridges. 

 II. " The Second Chromosome Group of Mutant Characters." Hy C. B. 

 Bridges and T. H. Morgan. III. "Inherited Linkage Variations in lh<- 

 Second Chromosome." By A. H. Sturtevant. IV. "A Demonstration of 

 Genes Modifying the Character 'Notch.'" By T. H.Morgani Pp. v-l- 

 sSB-l-ia plates. Publication No. 278. (Washington: Carnegie Institution 

 of Washington, 1919.) 



NO. 2639, VOL. 105] 



recent work upon it. Of the four parts into which 

 the book is divided, the most interesting is the first, 

 dealing with the gynandromorphic specimens that have 

 appeared in Prof. Morgan's and Dr. Bridges 's experi- 

 ments, and including a most valuable summary and 

 discussion of gynandromorphism in other animals. In 

 Drosophila it appears that about one individual in 

 every 2200 is gynandromorphic, but these gynandro- 

 morphs are most varied in their combination of male 

 and female characters. A considerable proportion of 

 those described are bilateral, with male secondary sex- 

 characters on one side and female on the other; a 

 smaller number are "fore and aft"; while the 

 majority are irregular mosaics, most often with a 

 preponderance of female characters. It is a remark- 

 able fact, however, that in Drosophila, contrary to 

 what is usual in animals of other groups, the two 

 gonads are always of the same sex — doubtless, as the 

 authors point out, in consequence of the ver\- early 

 separation of the primitive germ-cells in the Diptera. 

 As a result of this, it may happen that a fly is 

 externally almost entirely of one sex while containing 

 germ-cells of the other sex, so that Nature here con- 

 firms the conclusion reached by Meisenheimer and by 

 Koped from transplantation experiments, that the sex 

 of the gonad in insects has no influence on the 

 secondary sexual characters. Flies externally chiefly 

 male, but having ovaries instead of testes, court 

 normal females, but attract males. 



The authors believe that in all but very exceptional 

 cases gynandromorphs of Drosophila are derived from 

 fertilised eggs which would normally produce females, 

 i.e. from eggs containing two X-chromosomes, and 

 that the male portions arise from cells in which one 

 X-chromosome has been lost through an abnormal 

 mitosis in one of the early segmentation divisions. 

 The evidence for this conclusion is that in almost every 

 instance the sex-linked factors borne (according to 

 the chromosome hypothesis) by the two X-chromo- 

 somes introduced from the parents are distributed as 

 might be expected between the male and female por- 

 tions of the flv. For example, a wild-type female 

 (heterozygous for eosin eye and miniature wing) was 

 crossed with an eosin-miniature male. A gynandro- 

 morph among the offspring was female on the left 

 side, with red eyes and long wing, while the right 

 side was male with eosin eye and miniature wing. 

 The explanation offered is that elimination of the 

 maternal X-chromosome on the right side allowed the 

 recessive eosin-miniature characters borne by the 

 remaining X-chromosome to appear. Morgan's earlier 

 hypothesis of the production of gynandromorphs by 

 the entrance of two spermatozoa into the egg, and 

 Boveri's of the division of the egg-nucleus before con- 

 jugation with the sperm-nucleus, are excluded by the 

 fact that the non-sex-linked characters borne by the 

 two parents are not divided between the parts showing 

 different sexes. In respect of these characters, all 

 parts of the gynandromorph, whether male or female, 

 bear the dominant characters, whether they are intro 

 duced by the male or female parent. The analysis of 

 these gynandromorphs thus gives important confirma- 

 tion to the theory of chromosomes as bearers of 

 hereditary characters. It is remarkable, in this con- 

 nection, that although elimination of the paternal and 

 maternal X-chromosome is equally common, evidence 

 for the elimination of other chromosomes, which would 

 give mosaics in characters unconnected with sex, is 

 very rarely obtained. 



Analysis of the records of gynandromorphs in other 

 groups of animals shows that most are susceptible of 

 the same explanation. In a few cases some other 

 hypothesis, such as that of a binucleate egg, must be 

 invoked. It should be noted that in part i. there 



