2 DYNAMICS OF LIVING MATTER 



As the chemical character of life phenomena and the physical struc- 

 ture of living matter form the basis for the understanding of the dynamics 

 of living matter, it is natural that they should be the starting-point in 

 our lectures. 



As far as the specifically biological phenomena are concerned, 

 namely, the phenomena of development, self-preservation, and repro- 

 duction, it will be our aim to analyze them as much as at present pos- 

 sible from a physicochemical point of view. It may perhaps be 

 desirable before undertaking this task for us to state, as simply as 

 possible, some of the individual problems that will present themselves 

 for discussion, and the general method of their solution. 



We know that the eggs of the majority of animals cannot develop 

 unless they are fertilized, i.e. unless they are entered by a spermato- 

 zoon. We do not know how the spermatozoon causes the egg to 

 develop, but it is not to be expected that we shall gain an insight into 

 thesecauses except by trying to imitate by purely chemical and physical 

 means the effects which a spermatozoon has upon the egg. We shall see 

 that this has been accomplished in some forms. Under ordinary condi- 

 tions, the egg of Strongylocenirotus purpuratus, a sea urchin of the Pacific 

 coast, does not develop unless a spermatozoon enters it; but the fer- 

 tiUzing effect of a spermatozoon can be imitated in all essential details 

 by putting the egg for a minute into sea water to which a certain amount 

 of a fatty acid has been added and by subsequent exposure of the egg for 

 about half an hour to sea water whose concentration has been raised 

 by a certain amount. Similar results can be obtained in other forms. 



From a given egg can arise a specific organism only, the morpho- 

 logical and physiological quahties of which can be predicted with cer- 

 tainty, if we know the organism from which the egg is derived. We 

 call this fact heredity. Modern embryology has shown that the com- 

 plicated adult forms develop gradually from simpler forms, and by 

 following the development from the egg we readily understand how it 

 happens that the adult form is so much more complicated than the egg 

 from which it arises. The question which has recently puzzled bioloi, 

 gists is whether the egg has any structure which can be related to theVf 

 adult form. This seems to be true in the eggs of some forms, to thef 

 extent at least that from the various regions of the egg somewhat differ- 1 

 ent parts of the embryo arise. We do not know the causes which deter- 

 mine this relatively sUght differentiation inside of the egg, but we shall 

 see that everything indicates that these causes may be of a simple* 

 physicochemical order. In studying the mechanism of heredity, it is 

 perhaps of importance to realize that as far as the heredity of the earliest , 

 embryonic stage is concerned, it is almost, or exclusively, determined 



