736 



SCIENCE. 



[N. S. Vol. VII. No. 178. 



grasp their meaning when starting from his 

 point of view. 



It being, of course, admitted that chem- 

 istry should be so taught as to have its 

 principles firmly retained by the student, 

 the instructor should endeavor to place 

 himself in the student's position and strive 

 to see things from his standpoint. It is 

 immaterial how scientific the arrangement 

 of the course may be if such arrangement 

 does not follow the mental drift of the 

 average learner and appeal to his sense of 

 general fitness. It is for that reason that 

 I cannot sympathize with a separation of 

 the oxides of arsenic by an interval of 

 seventy-five pages from the other com- 

 pounds of the same element, as is done in 

 one of our best text-books. Such separa- 

 tion may suit the views of the distinguished 

 author and his brother chemists, but the 

 book is not written for them ; it is intended 

 for the use of beginners, and beginners do 

 not look at the subject in that apparently 

 disjointed way. 



Another difficulty with many of our text- 

 books is that they are much too full during 

 the early portions of the course. They 

 deal with expansions of, and exceptions to, 

 topics at a period when the topics them- 

 selves are fraught with entirely new ideas 

 to the student. 



Take, for instance, the question of 

 ' valency.' If my experience goes for any- 

 thing, it is better to allow the beginner to 

 conceive valency as a definite constant for 

 each element, and then at a later stage, 

 after considerable experience with things 

 chemical has been acquired, the subject 

 may be brought up again and more exten-. 

 sively discussed. 



Again, let us suppose that the student is 

 at work upon the subject of ' Phosphorus.' 

 Almost the first fact he learns is that phos- 

 phorus is attacked b^' oxygen with exceed- 

 ing readiness, and that an oxide of the 

 element results. 



Is it wise, therefore, to insert in the text 

 that ' phosphorus is incapable of uniting 

 with oxygen if the gas be perfectly pure and 

 free from aqueous vapor?' Would it not 

 be better to allow the beginner to become 

 as familiar as possible with the chemistry 

 of ordinary conditions before venturing into 

 those dimly lighted regions where ' chem- 

 ical purity,' ' perfect dryness,' ' exceeding 

 heat ' or ' exceeding cold ' are the disturb- 

 ing factors ? 



The. student tends to hold the instruc- 

 tor responsible for all irregularities in the 

 science, and, as a beginner, he resents am- 

 biguity. Exceptions and amendatory com- 

 ments both confuse and discourage him. 

 The time comes later on when to note the 

 peculiar character of this substance, or the 

 exceptional behavior of that, may be of real 

 interest to him ; but the establishment of 

 such an interest is a matter of slow de- 

 velopment, and care should be taken during 

 the early stages of instruction that great 

 masses of heterogeneous facts be not so 

 piled together as to cause no growth at all. 

 W. P. Mason. 



Kknsselaee Polytechnic Institute, 

 Teoy, N. Y., May, 1898. 



FBOFESSOB SCHENCK'S RE8EAECEES ON TEE 

 PBEDETESMINATION OF SEX* 



In view of the fact that Professor 

 Schenck's conclusions as to the power of 

 artificially determining the sex of offspring 

 have served as a nine-days' wonder to some 

 of the lay papers, it seems advisable to lay 

 before our readers a plain statement of his 

 argument, taken without comment from 

 the pamphlet which he has just published.f 

 It opens with the statement that it is im- 

 possible to command natural processes, but 

 possible by scientific means to exercise a 



* From Tlie British 3Iedical Journal. 



t Einfluss auf das GescldecliisverhaHnis. Von Dr. 

 Leopold Schenck, Professor an der k.k. Universitafc 

 und Vorstand des Institutes fiir Embryologie in 

 Wien. Magdeburs: ScbaUelmand WoUbruck. 1898. 



