VOLUME XLI ; NUMBER 4 
BOTANICAL GAZETTE 
APRIL, 1906 
CYTOLOGICAL STUDIES ON THE ENTOMOPHTHOREAE. 
II. NUCLEAR AND CELL DIVISION OF EMPUSA. 
EDGAR W. OLIVE. 
(WITH PLATE XVI’) 
THE division of the nuclei in Empusa has been found in the course 
of this investigation to resemble closely that described for Amoeba, 
Euglena, and other Protozoa. Such a primitive type of nucleus, 
which has been regarded as the typical protozoan form, has not so far 
been observed in the Metazoa, nor have any of the lower plants 
heretofore revealed a type of nucleus in which the “division-center” 
is permanently intranuclear. Such a type has been called by Boveri 
(:00, p. 183) a “‘centronucleus,” since it contains within itself a center 
of division which he assumes may be either in diffuse or concen- 
trated form. 
The varieties of protozoan nuclei and-the types into which they 
may be conveniently grouped are discussed by WILSON (:00), by 
CALKINS (:o1), and at some length by CALKmNs in a recent article 
(:03); hence we may concern ourselves here mainly with those forms 
which appear to show nuclear conditions nearest those in Empusa. 
SCHAUDINN published in 1894 an account of the division of the 
nucleolus-like body in the center of the dividing nucleus of Amoeba, 
and although he recognized that this appeared to play the chief réle 
in nuclear division, he reserved, till further comparative studies, his 
ideas on the mechanical details of the process. 
‘As in this paper I shall have to refer frequently to the figures already published 
in plates XIV and XV which accompanied my foregoing paper on The morphology 
and development of Empusa (Bot. GAZETTE 41: 192- -208. March 1906), I have num- 
bered the figures on this plate consecutively with them. 
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