364 M. M. Mercaur 
nucleus only the chromatin masses are drawn. Kept alive three days in 0,6 %, 
NaCl solution, acetic-carmine four hours, 0,6°/, NaCl solution 1/, day, coros. subl.- 
acetic acid, DreLarrenp’s haematoxylin. >< 404 diameters 
Fig. 96. A small individual with a single abnormal nucleus. (Compare Plate XX 
Fig. 92.) Friemmina’s stronger fluid, Maysr’s haemalum. 368 diameters. 
Fig. 97. An individual kept alive three days in 0,6°/, NaCl solution. The 
shape of the body and the position of the nuclei are unusual and may be abnormal. 
In the nuclei, which were in a late anaphase of mitosis, the chromatin masses 
are not carefully drawn. At the posterior end of the body one sees a depression 
which marks the position of the excretory aperture, an ovoid mass of the excretory 
granules, and the enlarged posterior vesicle of the excretory organ. The method of 
preparation was the same as for the individual shown in Fig. 95. >< 368 diameters. 
Fig. 98. A dividing individual, still active after living 51/, days in 0,6°/, 
NaCl solution. Division began the third day and the form of the body reached 
the condition shown upon that day; the animal remained apparently unchanged 
two days more and was then killed, stained and drawn. Three nuclei are in one 
daughter cell. The anterior daughter of one nuclear pair and the posterior daughter 
of the other are about to fuse. (In other instances more advanced stages of this 
fusion were found.) The four daughter nuclei seem normal; each has eight chromo- 
somes; each posterior daughter nucleus contains a nucleolus. Coros. subl.-acetic 
acid, DrenarieLp’s haematoxylin. X< 3865 diameters. 
Figs. 99-118. Abnormal Opalina obtrigona. 
(Coros. subl.-acetic acid, Denarrenp’s haematoxylin. All figures & 1600 dia- 
meters, except Fig. 111 which is a free hand sketch on a slightly smaller scale.) 
Figs. 99—101. Nuclei seeming almost if not quite normal. The network 
with thickened nodes is superficial and is probably chromatin, but the achromatic 
foam (not drawn), filling the whole nucleus, presents much the same appearance. 
Each nucleus shows from two to six discoid masses of chromatin upon the nuclear 
membrane. The bodies which are lightly shaded are chromatin discs on the far 
side of the nucleus. 
Figs. 102 and 103. Nuclei in which the chromatin plates upon the nuclear 
membrane are reticulate. In the center of each nucleus is a mass of granules 
probably chiefly achromatic. A little of the superficial, chromatin (?) net is shown, 
and a little of the achromatic foam is drawn in Fig. 103. It is hardly distinguish- 
able from the superficial net, except by its more central position and the smaller 
size of its meshes. 
Fig. 104. A nucleus in which the chromatin in chiefly in two reticulate 
masses, in one of which a central refractive body is seen. The reticulation of the 
lower mass is not shown. 
Figs. 105—109. Optical sections through nuclei showing similar conditions. 
In each is a central mass of granules probably chiefly achromatic and one or two 
bodies consisting of a central refractive sphere surrounded by a layer of chromatin 
which shows a denser net with more faintly staining interspaces. Bits of the 
achromatic foam are indicated in some of the figures. 
Fig. 110. A nucleus in which the achromatic granules are in two masses, 
connected by lines of similar granules. One sphere, with its chromatin either more 
compact or not well differentiated by the stain, is shown, as is also the achro- 
matic foam. 
