40 WHITMAN. [VoL. II. 
lating power ot the cell to the nucleus. This reserve is ren- 
dered imperative by other facts yet to be mentioned, for one of 
which we are again indebted to Gruber”? (p. 221). In summing 
up the results of his “Studies on Amcebe,” he states, “ that 
two very closely related species of Amoeba may have quite unlike- 
formed nuclei; while species differing widely in external form 
may have quite similar nuclei.” Plainly this is the contrary of 
what might be expected if the formative power lay exclusively 
in the nucleus. 
No Form-Correlation between Nucleus and Cytoplasm.—It 
may be put down as an indisputable fact that no form- 
correlation exists between nucleus and cytoplasm. Except dur- 
ing the process of division, the nucleus seldom departs from its 
typical spherical form. It divides and subdivides, ever repeat- 
ing the same steps and ever returning to the same round or oval 
form. So far as can be seen, its influence upon the cytoplasm 
is equal in all directions; and hence it would seem that its 
formative power, if it have any, could only contribute to the 
maintenance of the spherical form of the cytoplasm. How dif- 
ferent with the cell! It preserves the spherical form as rarely 
as the nucleus departs from it. Variation in form marks the 
beginning and the end of every important chapter in its history. 
While the nucleus repeats over and over again its little cycle 
of form-changes with mechanical regularity, the cell marches 
straight on from form to form, never returning, and never re- 
peating, differentiating, developing, and adapting itself at every 
step to its environment and to the work it is destined to per- 
form. From the egg onward through all the stages of histo- 
genesis and form-evolution, we search in vain for a single inti- 
mation anywhere that either the form of the organism or the 
forms of the individual cells are moulded by direct nuclear in- 
fluence. At the beginning of any ontogenetic series, when we 
get the most rapid and vivid displays of nuclear energy, we 
see that the environment of each cell is much more potent in 
determining its form than the nucleus. True, certain conditions 
of the environment may be said to be largely the result of 
nuclear activity ; and to this extent the nucleus may be said to 
determine, indirectly, the form of the cell. But this is very dif- 
ferent from saying that the nucleus has a direct controlling 
23 «Studien iiber Amoeben.” Zeitschr. f. wiss. Zool., XLI., p. 186, 1884. 
