38 WHITMAN. [ Vow. Tie 
a more important factor than the cytoplasm. There is not a 
single observation to prove what is so confidently asserted, that 
the nucleus gives the ‘Anstoss’ to division. This may be so 
and it may not. The observations prove, (I) that, in some of 
the higher Protozoa, the whole process of reproduction by fission, 
with exception of the initiatory steps, may be accomplished inde- 
pendently of nuclear action; and (2) that the tnttiatory steps 
cannot take place tf the nucleus and the cytoplasm are artificially 
separated. The whole truth is well stated by Nussbaum (No. 18, 
p. 516): “Kern und Protoplasma sind nur vereint lebensfahig: 
beide sterben isolirt nach kurzerer oder langerer Zeit ab.” It 
is clearly impossible therefore, by any such experiments as 
Gruber has carried out, to settle the question of the precise 
locus of the regenerative energy. 
On general theoretical grounds, as well as by the fact that 
enucleate forms are found among the Protista, we are compelled 
to accept the generally received view, that the nucleus is sec- 
ondary in origin. It may be true, as suggested by Gruber” 
(p. 151), that these so-called enucleate forms contain nuclear 
substance in solution, and that the first step in the phylogeny 
of the nucleus consisted in the formation of scattered granules, 
the coalescence of which would give rise to the single nucleus. 
But it is hardly necessary to add that we do not see how this 
(or any other) mode of explaining the origin of the nucleus as a 
secondary body can be brought into harmony with the idea that 
it embodies the whole regenerative energy of the cell. 
Interesting and instructive as are these experiments in the 
artificial division of the higher Protozoa, they do not alone fur- 
nish a satisfactory basis for general conclusions. They require 
to be supplemented by similar experiments on the simpler forms 
of Protozoa, and by much more complete observations than have 
yet appeared on the normal processes of fission and coalescence 
exhibited in the Heliozoa. In proof of this we have only to 
refer to Gruber’s own observations on Actinophrys sol™ (pp. 63- 
67) and Actinospherium eichhornit™ (pp. 381-382). Actinophrys 
20 Ueber Kern und Kerntheilung bei den Protozoen. Zetéschr. f. wiss. Zool., 
eS ae peeb2 1. 
21 Untersuchunge nueber einige Protozoen. Zezéschr. f. wiss. Zool.. XXXVIIL., 
P- 45, 1883. Also Zool. Anzeiger, No. 118, 1882, p. 423. 
22 Ueber Kerntheilungsvorgange bei einigen Protozoen. Zeztschr. f. wtss. Zool. 
XXXVIIL., p. 372, 1883. 
