698 THE AMERICAN NATURALIST. [Vor. XXXIX. 
Other authors as Scott (88), Hegler (:01), Bütschli (: 02), 
and Kohl (:03), also believe that the central body is a nucleus 
which divides mitotically but none has described the process as 
so closely similar to nuclear division in higher plants as in the 
account of Olive. Some of their results are criticized by Olive 
as based on preparations in which the stain was not properly 
differentiated or the sections were too thick. Among the recent 
writers Wager (:03) stands alone as holding that the nucleus 
divides directly (amitotically) by a process of simple fission. 
Both Kohl and Wager conceive the chromatin as in a network 
or convolute spirem which breaks up into segments which are 
drawn apart, thread by thread, quite a different process from the 
splitting of organized chromosomes. Other authors have held 
that the granules in the central body were chromatin although 
they were not willing to admit the structure as a nucleus. Thus 
Macallum (’99) found that the central body contained phosphor- 
ous and ‘masked iron" to a conspicuous degree and he, with 
other investigators, has shown that this structure resists the 
action of artificial gastric juice, solutions of pepsin, etc. These 
chemical reactions are considered confirmatory of the theory 
that the granular material is a proteid of a high order of or- 
ganization such as would be expected of chromatin. However, 
such chemical tests are very difficult to apply and do not seem to 
the writer so important in establishing the nature of the central 
body as does the careful study of its structure and activity during 
cell division. The objection that the central body lacks a mem- 
brane, universally present around resting nuclei of higher plants, 
is not regarded as vital by Olive. In the first place such a 
membrane may be found around the resting nuclei in young 
heterocysts and spores and its absence in vegetative cells is 
probably explained by the rapidity of the successive cell divi- 
sions. There are some recent writers, as Massart (:02) and 
Zacharias (: 00, :03) who are still unconvinced that the granules 
in the central body are chromatin and that the structure is the 
equivalent of a nucleus. Their papers and figures, however, 
clearly show that they have failed to find the detailed structures 
of other investigators. 
Fischer (97) has been the most conspicuous opponent of the 
