144 BULLETIN OF THE 



larves on rencontre tous les interuiediaires eutre les noyaux des extremi- 

 t6s et ceiix du milieu. Pea a pen le boyaii s'efface, le uo^'uu lui-meme 

 se retrccit et perd la regularite de ses contours a cause du plissement 

 de sa membrane ; a la fin la nucleine ne forme plus a I'interieur qu'une 

 masse compacte et homogene, a peu pres comme cela se pr6sente dans 

 la tete des spermatozoides." In both cases the degenerated nuclei are 

 found in stages of division ; in both, the cytoplasmic reticulum is distinct 

 only in old cells, and where these cells are biuucleate it is dicentric, 

 with filaments radiating from the nuclei. The dicenlricity of the binu- 

 cleate cells is a point to which Carnoy calls special attention (p. 229). 

 He considers that here the radiating filaments of the cytoplasmic retic- 

 ulum answer to the polar asters of karyokinesis, and that the nucleus 

 has the function of a centrosome. The same reasoning would apply 

 to the degenerated cells of the scorpion's serosa. 



The regressive metamorphosis undergone by the epithelial cells of 

 the ovarian capsule (Figs. 24-26) is very peculiar. Here, again, the 

 cell walls are affected in the same way as in the serosa and amnion, for 

 they are not distinctly seen until after the nuclei have degenerated. 

 Nearly all of the epithelial cells of an old capsule have two nuclei, which 

 are dissimilar in size and appearance (Figs. 24 and 25). The smaller 

 takes a rather deep, uniform stain, almost as dark as that of the chro- 

 matin of the other. A nucleolus is always present, and frequently 

 minute granules of chromatic substance. The uniformly staining char- 

 acter of the nucleus is doubtless produced by chromatic substance held 

 in solution by the karyoplasm, a condition of common occurrence with 

 degenerating nuclei. The larger nucleus (Figs. 24 and 25) takes only a 

 slight stain, owing to the scantiness of its chromatic substance, which is 

 present in the usual form of isolated granules and an imperfect network. 

 By examination of a large number of cells, I found nuclear differentia- 

 tion of every degree, beginning with nuclei almost alike in size and 

 stainability (Fig. 24), then passing to examples of marked dissimilarity 

 (Fig. 25), where the pale nucleus has become almost invisible, and the 

 smaller deeply staining one has attained a very sharp, definite outline. 

 As the pale nucleus becomes more and more shadowy, its shape becomes 

 irregular. Near cells of this sort others can be found which contain only 

 a single deeply staining niicleus (Fig. 26), tlie other having disappeared 

 altogether. In case of trinucleate cells, I have invariably found two of 

 them to be of the pale sort. 



I am unable to offer any other explanation of these changes than that 

 they are the result of degeneration or of decreased activity of the tissue. 



