November 15, 1S94J 



NA TURE 



59 



•mechanical actions of the human body, for the most part with a 

 degree of precision that would excite the astonishment of the 

 uninitiated ; we have also acquired a considerable knowledge 

 of the rough mechanical interactions of the individual organs of 

 the body, the mode of operation, so to speak, of the machinery 

 of organisms. But all that has been done, has been done only 

 up to a certain point ; and this point, at which we are brought 

 to a halt, is the cell. We have traced all phenomena of change in 

 matter, form, and force back to the point where they disappear 

 in the cell. But of what takes place in the muscle-cell, the 

 ganglion-cell, the lymph-cell, the gland-cell, the egg-cell, the 

 sense-cell, and so forth, we have not the slightest conception. 

 Moreover, we discover here, that even the minutest cell exhibits 

 all the elementary phenomena of life ; that it breathes and takes 

 nourishment ; that it grows and propagates itself ; that it moves 

 and reacts against stimuli. The elemen taiy riddles of life, 

 accordingly, have so far defied all research. 



" A balance thus cast of the results of past physiological 

 research does not, it must be admitted, exhibit a very 

 encouraging outlook. 



" But the resignation of physiology has been strengthened by 

 anothci prominent factor. This is the attitude of physiological 

 research to psychical phenomena. This attitude is at the present 

 moment a varying one. On the one hand, we still find secretly 

 cherished the vain hope of a chemical and physical explanatiou 

 of psychical processes, that is to say, of a reduction of them to 

 the motions of atoms, even though Du Bois-Reymond, in his 

 famous address on ' The Limits of Our Knowledge of 

 T\ature,' ' characterised such an understanding as utterly futile ; 

 while on the other hand we meet with an absolute resignation 

 in the face of this question — an attitude which is simply 

 a frank acceptation of the conclusion of Du Bois-Rey- 

 mond's, address. Owing to the authority of its author, the 

 ' Ignorabimus ' of Du Bois-Reymond has influenced great 

 numbers of inquirers, and produced in physiology a real 

 paralysis of research, so that the abandonment thus effected 

 of the solution of the old problem of explaining psychical 

 phenomena mechanically has caused physiology for the most 

 part anxiously and reverently to avoid any intrusion whatever 

 ■of psychological questions. On the one side, then, is the idle 

 hope of solving a problem which, despite its being as old as 

 human thought itself, research has not yet even touched ; and 

 on the other, an absolute renunciation of any treatment of the 

 problem whatsoever. 



Cellular Physiology. 



"If on the one hand we can Ijustly cherish the hope that the 

 increasing extension of the monistic world-view in natural 

 science will ward off the dangers of a reaction to the old 

 •viialism, the fact neveitheless remains that in treading the 

 beaten paths we are making no progres whatever in physio- 

 logy, and that we have stood still for years on the same spot, 

 and not approached a single step nearer our goal of explaining 

 the elementary phenomena of life. 



" We have reached a turning-point in physiological research 

 which could scarcely be made more prominent. The reappear- 

 -ance of vital force is a token of it. As before all great crises 

 of history portentous spirits appear to clairvoyant people, so in 

 our days the ghost of the old vital force has loomed up in the 

 fiiinds of some of our natuial inquirers. 



" But striking and obvious as the fact is that we can no longer 

 approach by the old paths of research an explanation of the 

 -elementary phenomtna of life, still, it is exactly as obvious anil 

 striking in what direction there is the only chance or hope of 

 our approaching our goal. 



" \Ve have traced the vital processes of man in physiology 

 back to the point where they aie lost in the cell. Now, what 

 is more reasonable than that we >hould seek them out in the 

 <:ell ? In the muscle-cell is hidden the riddle of -muscle-move- 

 ment, in the lymph-cell is hidden the causes of secretion, in 

 the epithelial cell is buried the problem of resorption, and so 

 ■on. The theory of the cell has long since disclosed that the 

 cell is the elementary foundation-stone of the living body, the 

 ■"elementary organism' itself, that in which the processes of 

 life have their seal ; anatomy anil evolution, zoology and 

 botany, have long since realised the significance of this fact, 

 and the wonderful development of these sciences has furnished a 

 brilliant proof of the fruiifulnessof this branch of inquiry. Only 



^ Veber die Grcnzcn dcs ^'atiircrkenncns. Rcdtn. Erste Folgc. 

 Leipsic, 1886. 



NO. 1307, VOL. 51] 



in physiology was the simple, obvious, and logical consequence 

 overlooked, and until very recently not practically applied, that 

 if physiology regards it at all as her task to inquire into the 

 phenomena of life, she must seek these phenomena at the spot 

 where they have their origin, at the focus of life-processes, in 

 the cell. If physiology, therefore, is not simply content with 

 confirming the knowledge which is already gained of the crude 

 mechanical actions of the human body, but makes it its object 

 to explain clearly elementary and general phenomena of life, it 

 can accomplish this object only as cellular physiology. 



" It may appear paradoxical, that although nearly half a 

 century has elapsed since Rudolf Virchow first enunciated in 

 several classical works the cellular principle as a basis of all 

 organic inquiry, a basis on which to-day, indeed, all our ideas 

 in pathology are constructed, physiology still is only just begin- 

 ning to develop out of a physiology of organs into a physiology 

 of cells. Vet this is the true and normal course of development 

 of science which always advances from the crude to the delicate. 

 And it would therefore be impardonable ingratitude, and a mis- 

 taking of the mode of development of human knowledge, if we 

 should seek in the least to underrate the high importance of the 

 physiological research of the past epoch, on whose shoulders in 

 fact we stand, and with whose results we more or less con- 

 sciously continue our work. Further, in our judgment of the 

 course of development of physiological research, a factor must 

 not be overlooked which controls the development of every 

 science, namely the psychological factor of fashion. The de- 

 velopment of every science depends on the stupendous influence 

 of great discoveries. Wherever we cast our eye in the history 

 of inquiry, we find that great discoveries such as, to take the 

 case of physiology, are represented in the works of Ludwig, 

 Claude Bernard, Du Bois-Reymond, and Liebig, deflect interest 

 from other fields and induce a great multitude of inquirers to 

 pursue research in 'the same direction, with the same methods, 

 especially when these methods have proved themselves so 

 wonderfully fruitful as in the cases adduced. Thus, certain 

 departments of inquiry become, in connection with epoch- 

 making performances, fashionable, and the interest of thinkers 

 in others subsides. But an equalisation in the course of time is 

 always re-effected, for every field of inquiry, every method of 

 inquiry is finite and exhausts itself in time. We have now 

 reached just such a point in physiology : the physiology of organs 

 is in its period of exhaustion. Also the method of cellular 

 physiology will exhaust itself in the course of time, and its place 

 will be taken by other methods which the present state of 

 the problem do not yet require. 



But for the present the future belongs to cellular physiology. 

 There are, it is true, inquirers who, although they are convinced 

 of the present necessity of a cellulur physiology, and see 

 perfectly well that the cell as the focus of the processes of life 

 must now constitute the real object of research, yet doubt for 

 technical reasons whether it is possible to get at the riddles of 

 life as they exist in the cell. It may, therefore, be justly demanded 

 that some way, some methods be shown with which a 

 cellular physiology can be founded. The doubt of the feasibility 

 of this undertaking is in great part the outcome of a phenomenon, 

 which, unfortunately we must say, has characterised physiology 

 ever since the death of Johannes Miiller, namely, the total lack 

 of a comparative physiology. Physiology has not yet entered 

 on this rich inheritance ol the great master. How many among 

 the physiologists o( the day are acquainted with other objects of 

 experiment than the dog, the rabbit, the guinea-pig, the frog, 

 and a few other higher animals ! To how many are the 

 numeiuus and beautiful objects of experiment known which the 

 wonderful luxuriance of the lower animal world offers ! And 

 yet, just among these objects are to be found the forms which are 

 best adapted to a cellular-physiological solution of physiological 

 problems. 



"Naturally, if we believe we are limited, in our cellular- 

 physiological treatment of the riddles of motion, digestion, 

 and resorption, solely to man and the higher animals, we 

 shall encounter in our investigation of the living muscle- 

 cell, lymph-cell, epithelial cell, and so forth, more or less in- 

 superable technical difficulties. And yet the splendid researches 

 of Heidenhain on secretion, digestion, lymph formation, and 

 so forth, have shown what good results the cellular-physio- 

 logical method can achieve even here. Well-planned his- 

 tological experiments, such as those which put the living 

 cell in its intact connection with the remaining woof of the 

 body under given conditions, and then investigate the results 



