766 



SCIENCE. 



[N. S. Vol. XV. No. 385. 



preparing the student for the study of 

 principles, the first of the two objections 

 urged against metallurgical laboratories, 

 that education ■ should be in principles 

 rather than in practice, falls to the ground. 



The second objection, that the conditions 

 of actual practice cannot be reproduced in 

 the laboratory would be unworthy of notice, 

 were it not offered by men of such weight 

 that even their error's must be considered. 



The error lies in supposing that this in- 

 struction aims to anticipate practice in 

 ■commercial establisliments : whereas its aim 

 is to facilitate instruction in metallurgical 

 principles by lectures and text-books. 

 There is no more reason for reproducing 

 "Commercial practice exactly in the metal- 

 lurgical laboratory than for reproducing in 

 the chemical laboratory the system of kilns, 

 towers and leaden chambers of the sul- 

 phuric acid works. But even from this 

 mistaken point of view the objection is 

 without weight. "With equal force it can be 

 urged that fire drill and military drill are 

 useless, because they cannot reproduce 

 exactly the actual conflagration, and the 

 actual carnage and confusion of battle. 



Another and important work of tha 

 metallurgical laboratory is to give a certain 

 skill in the use of the instruments of pre- 

 cision of the art, in pyrometry, colorimetry 

 and the microscopy of metals and alloys. 

 It seems to me nearly as imperative that the 

 metallurgist 's diploma to-day should imply 

 this skill as that the civil engineer's should 

 imply skill in the use of the transit. 



Finally, just as into a barrel full of 

 potatoes a quarter of a barrel of sand can 

 be poured, and then a quarter of a barrel of 

 water, so after the student's power of study 

 and note-taking in lectures has been thor- 

 oughly utilized, he still has power for much 

 of this different, this observational and 

 administrative laboratory work, in which 

 he absorbs and assimilates priceless infor- 

 mation like a sponge, and acquires along the 



path of least resistance and with but little 

 mental effort the needed metallurgical con- 

 ceptions. Henry M. Howe. 



A NEULECTED FACTOR IN EVOLUTION* 



An eminent Swedish zoologist, Dr. 

 G. Adlerz, in a very suggestive paperf has 

 recently called attention to some hitherto 

 neglected conditions affecting the varia- 

 bility of organisms. Starting from the 

 high degree of variability which has long 

 been known to obtain in organisms in a 

 state of domestication, Dr. Adlerz directs 

 attention to the similar phenomena pre- 

 sented by wild animals during the great 

 periodic increases in numbers brought 

 about by unusually favorable trophic and 

 meteorologic conditions. 



In regard to the domestic organisms Dr. 

 Adlerz gives expression to very generally 

 accepted views when he says: "The 

 changed conditions to which animals and 

 plants are subjected in a state of domesti- 

 cation must, of course, mean a decided 

 mitigation or even a complete cessation of 

 the struggle for existence. They are pro- 

 vided -with better and more abundant food 

 than in the feral state and the survival of 

 offspring is better insured. On the whole 

 therefore the individual organisms are able 

 to grow up under the most favorable cir- 

 cumstances. 



"No matter how completely the germ- 

 plasma may be shielded from external in- 

 fluences, it must, nevertheless, be suscep- 

 tible to changes in the kind and amount of 

 food, as Weismann admits, though he ap- 

 pears to lay little stress on this matter. If, 

 as seems probable, variations are ultimately 

 the resultants of physico-chemical processes 

 in the germ-cells, it would seem to be very 



* Contributions from the Zoological Laboratory 

 of tlie University of Texas, No. 33. 



t ' JPeriodisclie Massenvermehrung als Evolu- 

 tionsfaktor,' Biol. GentralU., 22. Bd., No. 4, Feb. 

 15, 1902, pp. 108-119. 



