No. 1] REGENERATIVE ENERGY. 37 
the general fact, that enucleate pieces of an infusorium are 
incapable of regenerating lost parts, while nucleate pieces soon 
regain the specific form. “ The nucleus is thus indispensa- 
ble to the preservation of the formative energy of the cell.” Gru- 
ber,!® whose experiments were begun at about the same time as 
those of Nussbaum, has reached the same general result. But 
one of Gruber’s experiments, which was at first supposed to 
show that regeneration is possible without the presence of a 
nucleus, brings out a fact of considerable importance. A Stentor 
ceruleus was selected, in which spontaneous fission had already 
begun, as indicated by the concentration of the rosary-formed 
nucleus into a simple oval form, and by the beginning of a new 
peristome at the middle of the body. A transverse section was 
made just in front of the new peristome, and so close upon the 
nucleus that it nearly all escaped from the cut surface of the 
posterior half of the Stentor. The anterior portion retained 
no part of the nucleus. The two parts were isolated, and on the 
following day each was found to have become a complete Sten- 
tor. As the plane of division was nearly the same as that which 
would have been followed if the process of spontaneous fission 
had not been interfered with, Gruber (No. 19, p. 13) finally con- 
cludes, contrary to his first interpretation, that this was not a case 
of regeneration, but of reproduction. The process of reproduc- 
tion once initiated by nuclear action may go on, so he thinks, to 
completion without further assistance from the nucleus. He 
insists, however, that the first impulse to division is given by 
the nucleus, since in all cases where artificial division is executed 
before the process of spontaneous fission begins, enucleate parts 
are incapable of regeneration. While finding no reason to doubt 
the accuracy of Gruber’s observations, I must contend that they 
do not warrant the conclusion so forcibly stated in the following 
words: “ Auf rein empirischen Wege werden wir hier vor die 
unumstéssliche Thatsache gestellt, dass der Kern der wich- 
tigste, dass er der arterhaltende Bestandtheil der Zelle ist” (No. 
19, p. 16). Allowing that regeneration is impossible in the ab- 
sence of a nucleus, that is no proof that the nucleus is the sole 
seat of regenerative power, nor is it a proof that the nucleus is 
XXVI., January, 1886, p. 485. Cf. also Sitz-Ber. d. Niederrh. Ges. f. Natur- u. 
FHleilkunde, 1884, p. 262. 
19 Beitrige zur Kenntniss der Physiologie und Biologie der Protozoen. Berichte 
a. Naturforsch. Ges. 2u Freiburg, 1.,H. 2, 1886. Also Biolog. Centraltl., 1V., p. 
717, and V., p. 137. 
