32 ROBERT W. HEGNER 



regardless of the character of the parental nuclei, but that the 

 mass relations between the nuclei and cytoplasm are such as 

 to lead to an equilibrium when a condition 'normal' for the 

 line is reached. 



3. Part of the chromidial net was also removed with the 

 cytoplasm. The elimination of chromidia, however, has no 

 apparent effect upon the characteristics of the offspring. 



4. When specimens are cut in two, each uninucleate piece 

 continues to live, and reproduces as rapidly as before the opera- 

 tion. The offspring, which are uninucleate, are slightly irreg- 

 ular in shape in the fi generation, but of normal shape in 

 succeeding generations. 



5. The descendants of large uninucleate pieces are at first 

 larger than those of smaller uninucleate pieces. This indicates 

 that the amount of cytoplasm within the parent influences the 

 size of the offspring. The quantity of cytoplasm is probably, 

 in turn, dependent upon the capacity of the shell. Within a 

 few generations, however, descendants of unequal pieces of the 

 same original parent are approximately equal in size, showing 

 that there is a definite normal size for the uninucleates in this 

 family. The establishment of this normal size appears to be 

 due to the interaction of the nucleus and cytoplasm resulting 

 in a gradual increase in the quantity of the latter until an equilib- 

 rium between the two is attained. Since, therefore, the nuclei 

 of the two original pieces were alike, the members of the two 

 lines derived from them finally reached similar proportions. 



6. Uninucleate specimens become binucleate after a varying 

 number of immediate offspring and of generations have been 

 produced. The uninucleate parents become binucleate dur- 

 ing a process of empty shell formation. The parent secretes 

 a new shell, usually smaller than itself, but the nucleus and 

 cytoplasm destined for this shell are withheld by the parent 

 and the shell is cast off in an empty condition. The parent 

 thus retains two nuclei and all of the cytoplasm. 



7. Specimens that have just become binucleate produce 

 binucleate offspring slightly larger than themselves. These 

 offspring, in turn, produce still larger progeny until after three 



