358 M. M. Mercaur 
has constricted or is constricting into two); in the other nucleus the chromosomes 
are already united into a ribbon. The difference in condition in the two nuclei 
is greater than usual, but is apparently not abnormal. The achromatic granules, 
in this case, were not carefully counted or drawn with entire accuracy. 1010 
diameters. 
Fig. 35. A pair of nuclei connected by a bent and somewhat spiral thread. 
In the anterior nucleus seventeen chromatin (?) masses (one may be the nucleolus) 
are seen, also several spindle fibers which were remarkably clear. This is an 
early prophase of mitosis. > 1010 diameters. 
Fig. 36. The posterior nucleus of a binucleated individual, in a late anaphase 
of mitosis. Eight chromosomes are in each end. But few of the spindle fibres 
were clear enough to draw and even these showed only faintly. The achromatic 
granules of only the upper half of the nucleus are shown. ‘These were unusually 
large and were irregular in shape, a fact difficult to show in a drawing at this 
scale. >< 1485 diameters. 
Fig. 57. A pair of nuclei connected by a very long and irregularly bent 
thread. Fourteen to sixteen chromatin masses are shown in the anterior nucleus, 
in the posterior nucleus the chromatin ribbon is still incompletely fragmented. 
Almost none of the achromatic granules in the anterior nucleus are drawn. In 
the posterior nucleus only the larger achromatic granules are shown. > 1010 
diameters. 
Plate XVII. 
Opalina intestinalis. 
Longitudinal division Figs. 38—43, transverse division Fig. 44. 
In drawings at this scale the nuclear phenomena cannot be accurately shown. 
Fig. 38. A very early stage of division, the anterior end of the body showing 
merely a slight indentation. The nuclei are in a late anaphase of mitosis. Coros. 
subl].-acetic acid, borax carmine. > 4tQ0 diameters. 
Fig. 39. A little later stage of division. The nuclei are in a late anaphase 
of mitosis. Coros. subl.-acetic acid, borax carmine. >< 460 diameters. 
Fig. 40. A still later stage of division. The nuclei are in a late anaphase of 
mitosis. Both anterior and posterior ends of the body are dividing. Coros. subl.- 
acetic acid, borax carmine. >< 460 diameters. 
Fig. 41. A dividing, individual, slightly abnormal, having been kept four 
days in Lock’s finid before killing. The nuclei are in a late telophase of mitosis. 
The body should before this have completely divided. The general form of the 
body, however, well represents the usual normal manner of division. Coros. subl.- 
acetic acid, IeLAFIELD’s haematoxylin. >< 460 diameters. 
Fig. 42. An almost completely divided individual. The nuclei are in an 
early telophase. This individual had been kept three days in sodium chloride 
solution before killing. Probably under normal conditions division would have 
been completed before the nuclei reached this stage. The general form is exactly 
similar to what is found in entirely normal animals in a late stage of division. 
Coros. subl.-acetic acid, DeLarretp’s haematoxylin. >< 460 diameters. 
Fig. 43. A daughter cell fresh from division, as is shown by the irregular 
contour of one side of the body where it was connected with its sister cell (com- 
pare Fig. 49). The nucleus is in a rather late anaphase, as is usual in such 
young daughter cells. This cell has received the posterior nucleus from the parent, 
