498 



SCIENCE 



[N, S. Vol. XXV. No. 639 



and fats is apparently large enough even 

 to keep up a steady luxurious surplus. 

 For the supply of proteid we find in the 

 actual conditions of life that man and 

 beast, if they can afford, provide them- 

 selves with quantities which physiological 

 chemists call liberal. This may or may 

 not be the quantity which nature requires 

 and approves of. Experiments have shown 

 that a number of men subsisted on the 

 half of such quantities. This latter might 

 be an indispensable minimum, just as there 

 is an indispensable minimum for all other 

 luxuriously endowed provisions of the 

 animal organism, and the liberal ingestion 

 of proteid might be another instance of 

 the principle of abundance ruling the 

 structures and energies of the animal body. 

 There is, however, a theory that in just 

 this single instance the minimum is meant 

 by nature to be also the optimum. But it 

 is a theory for the support of which there 

 is not a single fact. On the contrary, some 

 facts seem to indicate that nature meant 

 differently. Such facts are, for instance, 

 the abundance of proteolytic enzymes in 

 the digestive canal and the great capacity 

 of the canal for absorption of proteids. 

 Such luxurious provision for digestion and 

 absorption of proteids is fair evidence that 

 nature expects the organism to make 

 liberal use of them. Then there is a fact 

 that proteid material is stored away for 

 use in emergencies, just as carbohydrates 

 and fate are stored away. In starvation 

 nitrogenous products continue to be elimi- 

 nated in the urine which, according to 

 Folin, are derived from exogenous sources, 

 that is from ingested proteid and not from 

 broken-down organic tissues. An inter- 

 esting example of storing away of proteid 

 for future use is seen in the muscles of the 

 salmon before they leave the sea for the 

 river to spawn. According to Miescher 

 the muscles are then large and the repro- 

 ductive organs are small. In the river 



where the animals have to starve the repro- 

 ductive organs become large while the 

 muscles waste away. Here in time of 

 afi9uence the muscles store up nutritive 

 material for the purpose of maintaining 

 the life of the animal during starvation 

 and of assisting in the function of repro- 

 duction. This instance seems to me to be 

 quite a good illustration of the role which 

 the factor of safety plays also in the func- 

 tion of the supply of the body with pro- 

 teid food. The storing away of proteid, 

 like the storing away of glycogen and fat, 

 for use in expected and unexpected excep- 

 tional conditions is exactly like the super- 

 abundance of tissue in an organ of an 

 animal, or like an extra beam in the sup- 

 port of a building or a bridge— a factor 

 of safety. 



I therefore believe that with regard to 

 the function of supply of tissue and energy 

 by means of proteid food nature meant it 

 should be governed by the same principle 

 of affluence which governs the entire con- 

 struction of the animal for the safety of 

 its life and the perpetuation of its species. 



Before concluding I wish to add the fol- 

 lowing remark. It seems to me that the 

 factors of safety have an important place 

 in the process of natural selection. Those 

 species which are provided with an abun- 

 dance of useful structure and energy and 

 are prepared to meet many emergencies are 

 best fitted to survive in the struggle for 

 existence. S. J. Meltzek 



rockefelteb institute fob 

 Medical Research 



SGIENTIFIG BOOKS 

 SOME RECKNT BIBLIOGRAPHIES OF GEOLOGY 



Two very valuable bibliographies of interest 

 to all workers in geology have recently been 

 issued. The first is Mr. T. B. Weeks's ' Bib- 

 liography and Index of North American Geol- 

 ogy, Paleontology, Petrology and Mineralogy' 

 for the years 1901-5, inclusive. It constitutes 



