134 JOHN PllIESTLEY. 



it may be used to counteract the shrinking effect of dilute 

 solutions of acetic acid. 



The above statements, although made primarily concern- 

 ing the nuclei of carp's liver, may be understood as applying 

 to nuclei in general, whether still within their cells or not. 



With respect to nucleoli Auerbach has many new facts. 

 Instead of accepting 1 — 5 as the limits of numbers in which 

 nucleoli may occur, he regards — 16 as being more correct ; 

 but he adds that even 100 may be seen in some nuclei. The 

 enucleolar condition, besides occurring as a sign of de- 

 generation in the shrunken and thickened nuclei of horny 

 and some connective tissues, is seen in the early develop- 

 mental stages of various ova (of mammalia, articulata, and 

 vermes), as has been known since the time of Bergmann.^ 

 Auerbach has shoAvn that this condition obtains in the 

 batrachian ovum until cleavage has reduced the surface to 

 a finely granular mass. After a few days, however, certain 

 nuclei may be seen to have an ill-defined central cloudiness, 

 which, growing darker and darker, becomes at last the 

 nucleolus. In some cases the central haziness seems to 

 radiate towards the periphery : hence it is supposed that 

 the nucleolus is formed by the aggregation about the centre 

 of nucleolar substance which is derived either from the 

 periphery of the nucleus itself or from the inmost layer 

 of cell protoplasm. 



Besides increasing in the above manner, nucleoli may 

 multiply by fission. Of this there can be little doubt, for 

 Auerbach noticed a constant inverse relationship between the 

 size and the number of nucleoli within the nuclei. If two 

 nucleoli were present they were constantly smaller than the 

 nucleolus in uni-nucleolar cases ; while if three, five, &c., 

 were to be seen, some were distinctly larger than the rest, as 

 if the unevenness of number were due to the fission of some 

 only of the nucleoli. This division is associated with a move- 

 ment of the new nucleoli through the nuclear ground-sub- 

 stance, the cause of which is not understood (PI. XI, fig. 

 2 A). 



In addition to an increase in the number of nucleoli, the 

 converse operation was observed in certain cases, viz. the 

 fusion of several nucleoli into one.^ 



The functional significance of the increase of nucleoli is 

 not apparent. In the epithelium of the stomach and intestine 

 of the frog, Rana temporaria, the multinucleolar condition is 

 constant only during the height of summer and in the au- 



1 Miiller's ' Archiv,' 1841. 



^ This occurs in the fat-bodies and salivary glands of M. vomiioria. 



