224 Causes and Course of Organic Evolution 



nucleus. Another, that has been called the kinetonucleus, 

 seems to gather up or condense in it all the important hered- 

 itable characters of the cell, and later when sex-differentiation 

 and maturation of the cells are progressing it again fuses with 

 the cognitonucleus. We propose therefore to term it the 

 gametonucleus. A third, that is sister-nucleus to the last 

 in origin, becomes extended along the ectoplasm of the anterior 

 body-part, and forms there, along with a membranous expan- 

 sion of the ectoplasm, the characteristic sense-responsive or 

 correlating membrane of the group, from one or both ends 

 of which starts the highly sensitive fiagellum. We propose 

 therefore to term this the cogitonucleus. 



The researches of the above named observers show that 

 these three nuclei all remain connected T\dth each other by 

 fine chromatin threads, and so definite and common tubes of 

 energy-flow must constantly pass between and influence each. 

 But such differentiation of nuclear substance clearly suggests 

 the formation of three fundamental though interrelated body 

 masses, namely a somatic mass associated Tvith the cognito- 

 nuclear apparatus, an irritoreceptive and sense-correlating mass 

 associated T\'ith the cogitonuclear apparatus, and a hereditary 

 as well as reproductive mass associated Tvith the gametonuclear 

 apparatus. 



Here then, in a unicellular organism, are outlined the initial 

 morphological and physiological differentiations that corre- 

 spond to the general protojilasmic and nuclear or the bio-cog- 

 nitic, to the nervous or cogitic, and to the reproductive or 

 hereditary substances. 



An investigation of the Infusoria may next be made. As 

 outlined in the succeeding chapter, there occur in most if not 

 all genera of the group two nuclear constituents, the micro- 

 nucleus or micronuclei, and the meganucleus. Both are com- 

 posed largely of chromatin substance, but they differ much 

 in size as well as in number usually. Thus the micronucleus 

 may be single and small, but in genera like Spirochona and 

 Stentor three to twenty micronuclei may occur. The mega- 

 nucleus is usually large, and may at times become l)ranched, 

 elongated or other\\'ise modified. It evidently presides over 

 the general somatic or cognitic functions of the cell, for during 

 cell-life it is the most evident nuclear part. But during and 

 soon after conjugate fertilization it becomes broken down and 

 absorbed, to be again developed in the new individual. 



