346 



SCIENCE 



[N. S. Vol. XXX. No. 767 



the various lake forms of the long-spined 

 Daphnife to one species, viz., Daphnia longi- 

 spina. The winter forms of Daphnia hya- 

 lina, Hyalodaphnia (Daphnia) cucullata and 

 Cephaloxus can not be distinguished from each 

 other and they remain indistinguishable in 

 the spring till the water reaches a tempera- 

 ture of 14° to 16° C. As the temperature 

 rises above this, these indistinguishable forms 

 change in the course of two or three weeks 

 into the slenderer and lighter summer forms 

 which show all the characteristics of the dif- 

 ferent races to which they belong. In the 

 autumn aU return again to the common race 

 form which is found from December until 

 April. The autumn change extends over a 

 longer period than the spring change. 



Bosmina coregoni shows a decided seasonal 

 variation while B. longirostris shows only an 

 extremely slight one. 



The author reaches the conclusion that local 

 and seasonal variations arose during the 

 glacial epoch and are to be considered as the 

 reply of the organism to the greater differen- 

 tiation in environment ; in part at least to the 

 greater claims made by the rising temperature 

 on the floating power of the organism. The 

 return to the arctic form in winter shows that 

 seasonal variation is a condensed summary 

 of the development which the organisms have 

 undergone from the glacial period to the 

 present time. 



The long period of time covered by the col- 

 lections used for this study, and the large 

 amount of material that has been examined, 

 make this a most valuable contribution to this 

 phase of limnological investigations. 



C. JUDAY 



SCIENTIFIC JOURNALS AND ARTICLES 

 The Journal of Biological Chemistry, Vol. 

 VI., No. 4, August, 1909, issued August 12, 

 1909, contains the following : " The Spontane- 

 ous Oxidation of Cystin and the Action of 

 Iron and Cyanides upon it: The Action of 

 Metals and Strong Salt Solutions on the 

 Spontaneous Oxidation of Cystein," by A. P. 

 Mathews and Sydney Walker. In these two 

 papers various influences which affect the 

 spontaneous oxidation of cystin and cystein 



are described and the action explained in part. 

 Analogies with cellular oxidations are pointed 

 out. " On the Nature of the Chemical Mech- 

 anism which Maintains the Neutrality of Tis- 

 sues and Tissue-fluids," by T. Brailsford Eob- 

 ertson. The maintenance of neutrality in the 

 blood plasma and tissues is largely dependent 

 upon proteins. The reactions by which it is 

 brought about are explained. " Observations 

 on Uricolysis, with Particular Eeference to 

 the Pathogenesis of ' Uric Acid Infarcts ' in 

 the Kidney of the New-born," by H. Gideon 

 Wells and Harry J. Corper. Uricolytic fer- 

 ments could not be demonstrated in human 

 tissues : uric acid deposits in kidneys are not 

 therefore due to failure of such enzymes. 

 " Protein Metabolism in Cystinuria, II.," by 

 Horatio B. Williams and Charles G. L. Wolff. 

 Various metabolic tests carried out on a pa- 

 tient with cystinuria. " The Direct Colori- 

 metric Determination of Phosphorus with 

 Uranium Acetate and Potassium Ferrocy- 

 anide," by Eobert B. Gibson and Clarence 

 Estes. A convenient quantitative method 

 for total phosphorus in organic compounds. 

 " Notes on the Effect of Shaking upon the 

 Activity of Ptyalin," by Marie M. Harlow 

 and Percy G. Stiles. Adsorption is a factor 

 in explaining the curious observation that 

 some enzymes may be destroyed by mechanical 

 shaking. " The Estimation of Total Sulphur 

 in Urine," by Stanley E. Benedict. Oxida- 

 tion by copper nitrate very greatly facilitates 

 the estimation of total sulphur. 



SPECIAL ARTICLES 



SALIENT EVENTS IN THE GEOLOGIC HISTORY OF 

 CALIFORNIA 



There are few regions in the world where 

 the records of geologic history are more com- 

 plete than in California, for every major di- 

 vision is represented by marine sediments, and 

 many of them also by continental deposits. 

 This is made possible by the geographic posi- 

 tion between two ancient and persistent bodies 

 of water, the Pacific Ocean, and the Great 

 Basin Sea, which alternately encroached on 

 what is now California, each one supplying 

 that part of the record which the other 



