24 SYNOPTIC COLLECTION. 



of protoplasm may give rise in time to nerve force which 

 ultimately in the more specialized animals becomes local- 

 ized in a nervous system, and which manifests itself in 

 consciousness and will power. 



The Amoeba proteus usually has but one nucleus (fig. 3), 

 but sometimes a specimen is found with two nuclei (fig. 5). 

 Reproduction in this species probably takes place by fis- 

 sion. PI. 9, fig. 10, is a supposed Amoeba proteus in the 

 act of dividing. The separation of the thread connecting 

 the two parts occurred in ten minutes after the stage 

 represented in the figure. 



Gruber's important experiments on Amoeba proteus and 

 other Protozoa, in order to determine the part played by 

 the nucleus in reproduction, prove that by artificial divi- 

 sion only the portion possessing the nucleus is capable 

 of reproducing itself. The Amoeba was divided as 

 shown in PI. 9, fig. n, and the portion marked a lived, 

 while b drew in its pseudopodia and died. After many 

 experiments Gruber concludes that it is an incontrover- 

 tible fact that the nucleus is the species-preservative con- 

 stituent of the cell, and that to it is justly ascribed the 

 highest importance in the processes of fecundation and 

 inheritance. 1 If it is true that the continuance of the life 

 of the species depends upon the nucleus, then it follows 

 that in passing from the Protamoeba to the Amoeba a 

 change has taken place in the protoplasmic organism. 

 The generative power manifested by the cytode is cer- 

 tainly an indication of the existence of a generative sub- 

 stance making up a part at least of the cytode, and it 

 would seem as if this substance had become localized in 

 the nucleus of the Amoeba to form a distinct and species- 

 preservative organ. The remarkable differentiations of 

 the nucleus which are found in succeeding and more 



1 Ann. and Mag. Nat. Hist., (5), XVII, 1886, p. 473. Translated 

 from the Berichte der naturforschenden Gesellschaft zu Freiburg i. 

 B., i, 1886. See also Hofer, Jena. Zeitschr., XXIV (Neue Folge, 

 XVII), Heft i, 1889, P- 1O 5; an d Morgan, Regeneration, 1901, p. 

 65 (Columbia University Biological Series, VII). 



