68 BIOLOGICAL LECTURES. 



remark will meet with a decided denial from most morpholo- 

 gists ; nevertheless it seems opportune to warn them that the 

 problems they have before them can never be settled by purely 

 morphological methods. If my contention that all ontogenetic 

 problems must be approached by a most intimate combination 

 of the methods of physical, physiological and morphological 

 research is true, we are still far from having anywhere an 

 ideal biological investigator. If it is true that "we have been 

 mistaking ontogenetic effects for ontogenetic causes, what a 

 mass of speculation must probably be set aside. All that will 

 remain, in fact, will be the many most valuable and beautiful 

 results of observation made by our foremost morphologists. 



It is not intended to thus minimize in any way the great 

 and increasing value of morphological research ; what is really 

 meant is, that there is danger of overrating the importance of 

 morphology to the injury or exclusion of other disciplines of 

 paramount importance. If, as we must suppose, there is such 

 a perpetual flux and interflux of particles and molecules going 

 on throughout the plasma of an egg, owing to the metabolism 

 due to respiration and the consequent surface-tensional and 

 osmotic disturbances during the earliest steps of development, 

 it becomes inconceivable that any such morphologically con- 

 ceived and entirely hypothetical bodies as "ids," "idants," 

 "determinates," etc., can have a stable existence. The exist- 

 ence of such bodies as fixed entities of finite complexity is 

 absolutely disproved by experiments of the most varied charac- 

 ter in separating the first two or four blastomeres of .the egg, 

 since it is then found that, in each of these blastomeres, there 

 still inheres the power to produce a perfect embryo. The 

 hypothetical ids, determinants, biopJwrcs, gemmules, etc., must, 

 therefore, be supposed to be capable of being halved and then 

 quartered without destroying their potentialities. These and 

 numerous other difficulties that cannot be discussed here, 

 render it exceedingly probable that we must look in altogether 

 another direction for an explanation of the processes of 

 ontogeny, viz., to a study of the modes and conditions of the 

 manifestations of the energies that constitute the "life" of 

 the simplest organized forms. 



