OCTOBEB 4, 1907] 



SCIENCE 



437 



We can also understand why certain eggs 

 can develop without fertilization or show 

 natural parthenogenesis, while others re- 

 quire fertilization. The naturally parthe- 

 nogenetic eggs are those in which the 

 nuclein synthesis can be started without 

 the addition of an outside agency. In 

 analogy with the experience on seeds, we 

 may assume that the acid formed in them 

 after they have left the ovary is sufficient 

 to bring about the necessary hydrolytic 

 process or processes; either directly or 

 through the activation of enzyme. Such 

 eggs must also contain the necessary pre- 

 requisite for the normal occurrence of the 

 process of oxidation. In the eggs which 

 require fertilization we must probably dis- 

 criminate between two groups, one for 

 which the hydrolysis is sufficient to start 

 the nuclein synthesis, e. g., starfish, Tlialas- 

 sema, Polynoe; the second group for which 

 in addition provisions are to be made for 

 the processes of oxidation, by treating 

 these eggs with hypertonic sea-water con- 

 taining oxygen, e. g., sea-urchin, and 

 Lottia. 



I am of the opinion that this mechanism 

 of nuclein synthesis is the thread by which 

 we can find a rational way through the 

 maze of the otherwise bewildering mechan- 

 isms, characteristic of living matter; on 

 one hand, the phenomena of growth, on the 

 other, those of self-preservation. 



I will illustrate this by one example. 

 It can be proved that the nucleus itself 

 or one of its constituents acts as a catalyzer 

 in the synthesis of nuclein in the unfer- 

 tilized egg. This follows from the fact 

 that the velocity of the nuclein synthesis 

 in the fertilized egg increases in proportion 

 with the number of nuclei already present 

 in the egg. If the mass of the original 

 fertilization nucleus is m, the mass of 

 nucleins increases during the first segmen- 

 tation period to 2m, during the next to 

 4m, and so on, increasing with the ex- 



p'onent of 2; while the duration of the 

 various periods of segmentation differs 

 little and these differences have no rela- 

 tion to the mass of the nuclear material 

 formed during the period. This behavior 

 of a chemical reaction is characteristic for 

 such catalytic processes in which one of the 

 products of the reaction is itself a catalyzer 

 for the reaction. We must therefore con- 

 clude that the nuclei themselves or one of 

 their constituents are the catalyzer for the 

 nuclein synthesis or one phase of it. It is 

 possible that the nucleus catalyzes only the 

 phenomena of oxidation, and in as muchas 

 oxidations are the conditio sine qua non 

 of nuclein synthesis, this would explain the 

 autocatalytic effect of the nuclei upon this 

 reaction. A number of years ago I pointed 

 out that the nucleus seems to act as the 

 main (though possibly not the only) oxidiz- 

 ing agency of the cell. This influence of 

 the nucleus upon the nuclein synthesis, and 

 the role of this synthesis upon the preserva- 

 tion and continuation of living matter, ex- 

 plains one of the most mystifying char- 

 acteristics of the latter, namely, the phe- 

 nomenon of automatic reproduction of 

 cell's. Jacques Loeb 



University of Cat.tfobnia 



SCIENTIFIC BOOKS 



Introduction to Infinitesiinal Analysis: Func- 

 tions of One Real Variable. By Oswald 

 Veblen and N. J. Lennes. New York, 

 John Wiley & Sons. 1907. Pp. vii -f 227. 

 Cloth, $2.00. 



Elements of the InfLnitesimal Calculus. By 

 G. H. Chandler, M.A. Third Edition. 

 New York, John Wiley & Sons. 1907. Pp. 

 vi + 319. 



Differential and Integral Calculus with Ex- 

 amples and Applications. By George A. 

 Osborne, S.B. Eevised edition. Boston, 

 D. 0. Heath & Co. 1907. Pp. xii + 388. 



Advanced Algebra. By Arthur Schultze,, 

 Ph.D. New York, The Macmillan Com- 

 pany. 1906. Pp. xiv -I- 562. 



