Objection of Anuclear Regeneration in Stentor 55 
istomal, ciliated area, and he divided it in two halves. 
Since in this stage the chief nucleus, ordinarily monili- 
form, contracts into a round or bean shaped mass, 
Gruber was able to remove it completely from both 
halves. The division of the animal was effected in such 
a way as to produce about the same two halves as would 
later have been produced by spontaneous division. In the 
fragment which contained the original peristome the 
simple cicatrization of the wound was enough to repro- 
duce a complete individual. In the other fragment which 
contained the posterior extremity the wound closed in 
the same way and the anterior extremity continued its 
development until the peristomal area and the buccal 
spiral were completely formed.?® 
This result seemed to contradict the view that the 
formative action of a nucleus, as a developmental center 
for the unicellular organism, was exerted continuously 
throughout the whole duration of development. But the 
following considerations show that this premature con- 
clusion is quite fallacious. 
We should remember in this connection another ob- 
servation of Gruber. He cut off from the anterior end 
of a Stentor a fragment absolutely without a nucleus, but 
containing a small portion of the peristomal band. The 
cicatrization of the wound was followed by the ordinary 
contraction of the fragment and thereby the small portion 
of the peristomal band was given the appearance of a 
complete Infusorian such as would be formed by regen- 
28Gruber: Uber kiinstliche Teilung der Infusorien. Zweite 
Mitteilung. Biol. Centralbl. Band, V, No. 5; May 1, 1885. P. 139— 
140; und: Beitrage zur Kenntnis der Physiologie und Biologie der 
Protozoen; Berichte der Naturforschenden Gesellsch. zu Freiburg 
i. B., Freiburg i. B., Mohr, 1886, P. 13—14. 
