248 



SCIENCE 



[N. S. Vol. XLII. No. 1077 



dred cancer patients all the time and almost 

 without exception within proved cancer strains, 

 this reasonable probability is raised to an al- 

 most indisputable fact; and whether or not 

 my strains of housemice have behaved in hy- 

 brid crosses in accordance with the established 

 canon has no bearing whatever upon the be- 

 havior of cancer. It is an academic dispute 

 which lies in quite another field. 



In regard to my use of the terms " domi- 

 nant " and " recessive " with respect to cancer 

 behavior: it is almost the established convic- 

 tion to-day that these terms are descriptive 

 and not dynamic, and they furnish in the de- 

 scription of the behavior of cancer in heredity 

 a graphic and convenient tool. That is prob- 

 ably all they furnish in the exposition of any 

 problem in heredity. They may be discarded 

 for even that service within the next few years. 



The chief value in the study of cancer of 

 the use of a partial Mendelian background of 

 comparison (although the details may be under 

 dispute) is to show to those most interested 

 how far back in a strain cancer may lie and 

 still be transmitted, and by what sorts of 

 crosses this can be done, and to make it plain 

 that in deciding upon the inheritability of hu- 

 man cancer and of the method of elimination 

 of cancer from a family, one can not take as 

 a criterion of judgment whether or not the im- 

 mediate parents exhibited cancer. 



I do not desire or make a strict Mendelian 

 interpretation of my results, indeed I should 

 deplore such an interpretation. I have used 

 Mendelian comparisons (1) to make clear the 

 influence of a more or less remote ancestry 

 upon later generations of progeny ; (2) to show 

 how cancer, like albinism, has been transmitted 

 in my strains through generation after genera- 

 tion by individuals who did not exhibit it; 

 and (3) to demonstrate how cancer thus 

 transmitted finally leaps into expression in the 

 offspring of a pair neither of whom expresses 

 cancer, but both of whom bear it potentially. 



The approximation to even the most con- 

 servative Mendelian expectation is strikingly 

 close for such a characteristic as cancer. 



Maud Slte 



The Otho S. A. Spraque 

 Memorial Institute 



SCIENTIFIC BOOKS 

 The Mathematical Theory of Investment. By 



E. B. Skinner. Boston, Ginn and Company, 



1913. Pp. ix+245. 



Skinner's Theory of Investment is divided 

 into four parts: 1. Algebraic Introduction. 

 2. Interest and Annuities. 3. Probability and 

 Its Applications to Financial Problems. 4. 

 Tables. 



The Algebraic Introduction gives a sketch 

 of arithmetic and geometric progressions, 

 limits, series in general (with particular em- 

 phasis upon the binominal, exponential and 

 logarithmic series), logarithms and graphical 

 representation. 



In the discussion of Interest and Annuities, 

 the old standard problems are taken up, includ- 

 ing such applications as amortization, the 

 valuation of bonds, sinking funds, deprecia- 

 tion, building and loan associations. 



In the third part a short introduction to the 

 theory of probability precedes the discussion 

 of life annuities and some other problems in 

 life insurance. 



There are 12 tables, mostly Y place, for deal- 

 ing with interest (simple or compound), dis- 

 counts, and present values, annuities, and life 

 insurance data. 



This work is elementary, clearly written and 

 satisfactory throughout for a general intro- 

 duction to the problems with which it deals. 

 In regard to insurance, one finds just about 

 enough for an introduction without too much 

 to take the cream off a real course in insur- 

 ance. The subject of interest and annuities, 

 however, is handled in such detail that further 

 work upon the subject might not be needed. 



The work is entirely formal, that is to say, 

 no reference is made to economic conditions 

 which afl^ect the real rate of interest. The 

 question, for instance, of the price level is not 

 mentioned. No theory of interest can be other 

 than mere form, without substance, apart from 

 a discussion of the effect of a change of price 

 level upon the investment yield, both as to 

 principal and interest. 



In discussing the valuation of mining prop- 

 erties the author says : " When a sum of money 

 is loaned the person making the loan not only 

 receives interest at a stipulated rate at the 



