THE CELL 15 



merit in explanted tissue has been kinematographically studied. Such 

 cells use the threads of fibrin of the plasma medium as guides in their 

 wanderings. While the cells of explanted tissues live and multiply, 

 it is doubtful how far they show the characteristics of the particular 

 tissue. It is said the new-formed cells take on an indifferent character, 

 and never show the characteristic formation of the mother organ. 

 If true cultures of the cells' organs could be obtained, the method 

 would lend itself admirably to the study of histogenesis, metabolic 

 processes, age and death phenomena of cells. It has, however, been 

 claimed recently that contractile cells which must be considered 

 muscular have been obtained by culture of the cells of the heart of the 

 embryo rabbit (Fig. 11). 



The phenomena of movement, irritability, the digestion and ab- 

 sorption of food, its assimilation and dissimilation, the excretion of 

 waste materials, growth and reproduction, are essentially those of 

 living matter. Physiology i the study of such life processes. 



These processes in part conform to the laws of physics and chemistry 

 which have been found to govern matter generally. Of much, how- 

 ever, at present the explanation is not clear, and to expess the reactions 

 of living matter terms such as " biological force," " vital force," and 

 " biotic energy," are often employed. The use of such terms does not, 

 or should not, indicate that there is any deep and unfathomable mystery 

 about life phenomena other than that hitherto insoluble mystery 

 which enwraps the universe, and conceals from us the ultimate origin 

 and the nature of what we choose to term matter and energy; rather, 

 it means that the physico-chemical laws governing matter have not 

 yet been sufficiently found out to render clear the interpretation of 

 living processes. With each fresh advance in natural science the 

 phenomena of life are being correlated with phenomena of non-living, 

 matter, and there can be no doubt that with a fuller knowledge of 

 chemical and physical laws many of the processes now labelled " vital " 

 will be capable of being grouped under these laws. To say this does 

 not lessen the dignity of the conception of life; rather, it exalts, by 

 unifying, our general conception of the universe. A certain arrange- 

 ment of matter acts as a transformer through which the phenomena 

 of life become manifest. The universal source of energy, whatever 

 it may be, becomes transformed into the various manifestations of 

 energy which we call life, including the workings of Mind. In dead 

 matter the transformations of energy are otherwise in character, but 

 the play of energy is no less ceaseless in character, no less beyond final 

 explanation, no less worthy of veneration. Nothing is common or 

 simple to him who has really probed into the secrets of Nature. 



The following has been put forward as a tentative speculation 

 on the origin of life : 



The whole world of living plants and animals depends for its present 

 continuance upon the synthesis of organic compounds from inorganic 

 by the green colouring matter of the plant acting as a transformer of 

 light energy into chemical energy. This present stats of affairs must 

 have been evolved from something more simple existing at the com- 



