194 C. CLIFFORD DOBELL. 
plastin matrix, which extends through the cell. This net- 
work represents the compact nucleus which we are accustomed 
to see in other organisms. ‘To speak of it as a ‘ chromidial 
net,” as does Gonder, is, to my mind, misleading. For there 
is absolutely no indication that it is im any way comparable 
to the structure known as a chromidial net in Thalamophora, 
etc. It is merely a modification of the branched form of 
nucleus. 
The branching type of nucleus has been long familiar to 
cytologists. It is well seen in the cells of certain insects, as 
we know from the work of the Hertwigs, Brant, Eimer, 
Balbiani, etc. (Cf. R. Hertwig’s description (10) of the 
“amoeboid” nuclei in the Malpighian tubule cells of Pieris 
brassice.) But the most instructive comparisons are to be 
made with the nuclear apparatus of other Infusoria. 
Maupas (12), Gruber (8, 9), and others have described 
various forms of diffuse nucleus in the Infusoria. One of 
the most careful descriptions is that by Gruber (9) of the 
hypotrichous ciate Holosticha (Oxytricha) scutellum, 
Cohn. In this organism both meganucleus and micronucleus 
lie scattered in fragments through the cytoplasm during 
vegetative existence. Before division, however, the frag- 
ments come together, forming a single mega- and micro- 
nucleus, both of which then divide, subsequently fragment- 
ing once more in the daughter individuals. This formation 
of a compact nucleus before division does not appear to take 
place in all “ multinucleate” forms, e.g. Loxodes. In 
Trachelocerca, Uroleptus, and Epiclinites also the 
nucleus is diffuse (Gruber, 9). 
It is in the parasitic Infusoria, however, that the most 
interesting forms for comparison with Chromidina and 
Opalinopsis are to be found. In Feoettingeria acti- 
niarum, Clap.,! a nuclear apparatus very like that of Opali- 
nopsis has been described by Caullery and Mesnil (8). In 
1 = Fettingeria (Plagiotoma, Conchophthirius) actiniarum, 
Claparéde emend. Caullery et Mesnil. ‘The animal lives in the celenteron of 
various sea-anemones. 
