MUSEUM OF COMPARATIVE ZOOLOGY. 345 



tunity to study nuclear division, and usually at some distance from the 

 injured spot. Also on preparations of the normal cornea made with 

 gold chloride, certain nuclei appear larger than the others, and are 

 composed of clusters of lustrous corpuscles, somewhat smaller than the 

 smallest nucleoli. In addition there are found simply curved and 

 S-shaped lustrous rods of the same diameter as the granules, with 

 knoblike ends. These are often radially arranged. 



In the rabbit's cornea undergoing regeneration occur similar phe- 

 nomena. When the granules are not too close together one sees be- 

 tween them the larger nucleoli. Moreover, only a part of these granules 

 are free like the nucleoli ; others appear as small thickenings in the net- 

 like system of filaments which form the nuclear stroma. In other cells 

 the nuclear membrane and the nucleoli are no longer to be found, and 

 in place of a granular nuclear substance there is an irregular, lustrous, 

 starlike structure, half as large as the nucleus previously was. The rays 

 of this star are either plump, or, if slender, have terminal swellings, and 

 may be elongated and spindle-shaped. A clear area, surrounding this 

 figure, more or less sharply defined from the surrounding protoplasm, is 

 the remnant of the previous nucleus. The fibrous mass becomes short- 

 ened and thickened, and thus assumes the shape of a double convex lens, 

 or a sphere, of meridionally arranged rods and granules. An equatorial 

 fission separates this structure into hollow hemispheres, — each a sort of 

 fibrous basket. The granules have now become less abundant, having 

 probably been converted by fusion and elongation into filaments ; at 

 least the latter are more numerous than previously. The parting fila- 

 ments are often swollen, at other times they end in attenuated ex- 

 tremities. They vary in length, and may anastomose with each other. 

 The separation is not effected at the same instant in all the fibres, a 

 part retaining their connection for some time. The basket structures 

 separate, and after the parting of the last delicate traces of the equa- 

 torial ends of the fibres their peripheral ends terminate in a cluster of 

 lustrous granules, or a crescent-shaped body, and are no longer distin- 

 guishable from each other. The crescent-shaped body grows at the 

 expense of the fibres, and there results in place of the fibrous basket an 

 oval, jagged body — the new nucleus — surrounded with a clear area. 

 This new nucleus is a sort of shallow cup of homogeneous substance. 

 The clear area is the result of the constriction and division of the area 

 which previously surrounded the two fibrous baskets. The cell undergoes 

 division during the conversion of the basket into a homogeneous, jagged 

 body. The latter subsequently changes into a larger vesicular nucleus. 



