354 



SCIENCE 



[N. S. Vol. XLV. No. 1163 



297.4 ±1.0. The value of this quantity de- 

 rived in 1910 from observed deflections of the 

 vertical in the United States was 297.0 ± O.5.* 

 The very close agreement between these two 

 independent values, an agreement which is 

 well within the probable error of either one, 

 is strong evidence both of a very high degree 

 of accuracy of each and of very successful 

 elimination of systematic errors. 



Helmert's value of 1915 is 296.7 ± 0.4. It 

 is based upon 410 gravity stations in various 

 parts of the world. These stations were 

 selected carefully with reference to their rela- 

 tion to topography, a precaution which is nec- 

 essary with Hehnert's method of computation, 

 though not with Mr. Bowie's method. Hel- 

 mert's method of computation differs radically 

 from that used by Mr. Bowie, yet the two end 

 results are in close agreement. 



It is the writer's opinion that Mr. Bowie's 

 monograph on the topic " Investigations of 

 Gravity and Isostasy," is a notable contribu- 

 tion to geodesy. It furnishes a new and 

 broader basis for further studies by geologists 

 and students of geophysics. It furnishes new 

 evidence of the steadily increasing skill and 

 energy with which the Coast and Geodetic 

 Survey is attacking the scientific problems 

 which come within its scope. It is hoped that 

 this article touching upon a few of the main 

 points in the monograph will help arouse such 

 interest as will lead to study of the monograph 

 itself. John F. Hayford 



College op Engineeking, 



NOKTHWESTEEN UnIVERSITT, 



EvANSTON, III. 



THE NATIONAL ACADEMY OF 

 SCIENCES 



The following abstracts have been received 

 of the papers to be presented at the stated 

 meeting of the National Academy of Sciences 

 to be held in Washington on April 16, 17 

 and 18. 



Sex-Determination and Sex-Differentiation in Mam- 

 mals: Feank R. Lillie, The Uaiversity of Chi- 

 cago. 



■4 ' ' Supplementary Investigation in 1909 of the 

 Figure of the Earth and Isostasy, ' ' p. 77. 



Sex-determination in mammals is zygotic, but it 

 does not imply an irreversible tendency to the in- 

 dicated sex-differentiation. Intensification of the 

 male factors of the female zygote from the time of 

 onset of sexual differentiation by action of male 

 sex hormones may bring about very extensive re- 

 versal of the indicated sex-differentiation. This 

 result is attained by a study of the twins of cattle. 

 The way is open for an experimental examination 

 of the limits of such reversal, and for an examina- 

 tion of the possibilities in the case of the male 

 zygote. 



Sporogony of Malaria Parasites: Photomicro- 

 graphs of Infected Anopheles: W. V. King, 

 Ph.D., Bureau of Entomology. (Introduced by 

 L. O. Howard.) 



The cycle of development through which malaria 

 parasites pass in the body of anopheline mosqui- 

 toes has been described in more or less detail by 

 several authors. The illustrations of the develop- 

 mental phases are, however, mostly taken from 

 drawings which are often schematic and in some 

 oases misleading. The opportunity is therefore 

 taken for presenting the accompanying series of 

 photomicrographs representative of the various 

 stages in the complete sporogonie cycle, and a brief 

 explanatory descrijjtion of the development as ob- 

 served in fresh preparations of infected mosqui- 

 toes. A few differences from the description as 

 given in some of the texts have been observed and 

 these are substantiated by the illustrations. The 

 work was done in the laboratory of Dr. C. C. 

 Bass, Tulane University, New Orleans. 



The Great Barrier Beef of Queensland, Australia: 



W. M. Davis. 



In recent years a number of students of coral 

 reefs have concluded that the Great Barrier Reef 

 of Queensland has been built up on a sUghtly sub- 

 merged platform, of origin independent of coral 

 growth and presumably similar to that of the con- 

 tinental shelf which borders the eastern coast of 

 Australia, south of the limits of coral reefs. 



There is, however, good reason to think that the 

 present immature reef is an upgrowth from a sub- 

 merged mature reef plain of an earlier time, if the 

 changes of level that have taken place in the high- 

 lands inland from the coast are considered. Pol- 

 lowing the studies of E. C. Andrews, of Sydney, 

 the highlands of eastern Australia in the region 

 near the boundary between New South Wales and 

 Queensland show the work of several cycles of 

 erosion, each separated by an uplift of several 

 hundred or a thousand feet. When these uplifts 

 took place, the off-shore belt must have been de- 



