78 Vitality and Organization of Protoplasm. 



know, furthermore, that after fertilization has been accomplished the 

 fertilized egg-plasm is found to be again bilaterally organized, and on 

 its way to divide into two unilateral halves, represented by the two first 

 blastomeres. The final result of the entire ontogenetic process proves 

 that an intimate interblending of male and female germ-plasms has 

 been somehow achieved during fertilization. When and how does this 

 interblending of the two plasms take place? 



The medial part of the spermatozoon in contact with natural egg- 

 plasms is seen to divide, and to form two centrosomes from which the 

 fertilizing activity starts, manifesting itself in granular commotion and 

 formation of atrospheres extending more and more deeply into the egg- 

 plasm, involving more and more of it in the bisexual transformation. 

 The matured egg-plasm proving at the beginning of the process to be 

 bilaterally organized, it is not far-fetched to conjecture that the sperm- 

 plasm, embodied in the matured medial part of the spermatozoon is like- 

 wise bilaterally organized, and that its division into two centrosomes is 

 really a division into the unilateral halves. This, indeed, becomes finally 

 evident, as the result of the fertilizing transformation; and concomitant 

 blending of female with male plasm, which takes place around the cen- 

 trosomes of the medial portion of the spermatozoon ; as this result proves 

 to be actually the formation of the two first bisexual and unilateral 

 blastomers. 



Centrosomes have always to be considered germinal centers, and the 

 formative activity around them as one of gradual reintegration towards 

 the reproduction of the adult organism. Centrosomes may arise in pro- 

 toplasmic beings under whatever conditions go to favor the origination 

 of new formative centers; and they may dissolve again when their sub- 

 stance becomes assimilated by stronger formative activities than their 

 own. This has been proved by various experiments, such as those of 

 Morgan after the application of solutions of salt. In normal forma- 

 tive processes, however, the number and localization of centrosomes is 

 definitely predetermined. 



It remains still unexplained how the definitely organized egg-plasm 

 can come to be intimately interblended with male-plasm, as is the case 

 in bisexual reproduction. How can a definitely organized structure 

 blend with another definitely organized structure without both losing 

 their definite organization? This is a problem inexplicable by any me- 

 chanical and aggregational theory. It has been shown that all attempts 

 in that direction have necessarily failed, and that we are face to face with 

 a specific vital activity, which would have remained utterly enigmatic 

 had not experimental ontogeny furnished us with data that essentially 

 assist its understanding. For it has been experimentally proved that 

 the definite bilateral organization of egg-plasm being upset, all parts or 

 fragments of it become totipotent germs, capable of reproducing entire 

 embryos. In fertilization it is egg-plasm tliat has become totipotent 

 in all its parts after its bilateral organization has been upset by the in- 

 fluence of the spermatozoon ; it is this totipotent plasm that enters into 



