382 CALKINS. 



cording to Gruber, unite into a common body previous to divi- 

 sion and are then halved. 



The Cihata are highly specialized Protozoa and it is probable 

 that, among them, the primitive distributed nucleus is very un- 

 common ; we should expect to find this condition in the simpler 

 and less differentiated forms like the flagellates or the lowest 

 plants. In the latter, especially the bacteria and the closely 

 allied Cyanophyceae, Biitschli ('90 and '96), confirmed by 

 Zacharias ('90), described cells possessing a distinct proto- 

 plasmic structure enclosing numerous granules which he found 

 to be chromatin. Biitschli regards these cells as nuclei with 

 only a fine layer of protoplasm around the outside. The chro- 

 matin is laid down on what appears to be the cytoplasmic retic- 

 ulum but which according to his view, would be linin. How- 

 ever this view may be in regard to the bacteria it cannot hold 

 for cases of distributed nuclei among the Protozoa. 



A flagellate belonging to the genus Tetrainitiis possesses a 

 nucleus of the same distributed type. The protoplasmic struc- 

 ture of this flagellate is strikingly similar to Biitschli's figures 

 and photographs of Chromatiiuii and other bacteria. The pe- 

 riphery is characterized by a distinct alveolar layer consisting of 

 vacuoles of regular size and arrangement, and the walls which 

 bound them. The central portion is made up of alveoli of 

 various sizes and is much looser in texture than the outer layer 

 (Plate XXXV, Figs. 1-4). After fixation with Hermann's fluid 

 and staining with Flemming's triple stain, this cytoplasmic 

 structure appears yellowish or of an orange tone. In the endo- 

 plasm the substance of the alveoli appears to have run together 

 at one point to form a more compact, denser aggregate which, 

 with the stain used, appears homogeneous (Fig. i A). With the 

 iron-haematoxylin the fused portion becomes more conspicuous 

 although not more deeply stained than the cytoplasmic reticu- 

 lum. It appears to be a coalescence of cytoplasmic microsomes. 

 No inner structure could be made out, although in some cases 

 a lighter area (Fig. 2) was faintly indicated in the center. In 

 some individuals the body in question appears biscuit-shaped 

 as though undergoing division (P"ig. 4). 



