ID RALPH E. WAGER. 



An explanation of the phenomena here described, though not 

 easy to find, appears to be as follows : The nucleolar bodies when 

 they appear within the nucleus in such large numbers are in 

 small part products of the metabolic changes within the nucleus 

 but in greater part are doubtless certain liquids which have osmot- 

 ically penetrated the nuclear membrane and been coagulated by 

 the killing and hardening fluids. These substances may serve as 

 food for the nuclear activities and, in their later history, as stores of 

 energy for the embryo. The ultimate disposition of these bodies 

 in the cell would support this view. No attempt was made to 

 determine their chemical nature by staining methods as the mate- 

 rial required was lacking. Similar nucleolar bodies have been 

 described by Montgomery ('98) in the case of certain nemertean 

 worms.^ By staining methods he seems to have shown quite 

 conclusively that they are liquids taken in through the nuclear 

 membrane and are of the same nature as the yolk balls which 

 occur very abundantly within the cytoplasm. Such yolk masses 

 are growths or accumulations and as such are different than the 

 pseudo-cells which are found in the egg under discussion. 



These nucleolar bodies usually appear in the first stage of the 

 metamorphosis of the cell or nucleus. As indicated above, it is 

 not probable that the chromatin collects in small spherules to add 

 to the number. The nuclear membrane in this stage is frequently 

 broken and very irregular. The second stage is due to a partial 

 fusion or flowing together of these bodies. The rupture of the 

 nuclear membrane results in the liberation of the nuclear liquids, 

 in the case of the metamorphosis of a whole cell, which are 

 apparently separated by some chemical factor so that the chro- 

 matin substance becomes spread out in the periphery of the 

 hemisphere in which the nucleus lies, thus accounting for the 

 darkly staining properties of this portion of the structure. At 

 the same time the cytoplasm itself becomes chemically changed, 

 for it reacts slightly to a chromatin stain. The nuclear sap does 

 not appear to take any differential stain but is disseminated 

 through the cytoplasm of the cell. 



That this is the true explanation is evidenced by cross-sections 



1 Principally in Stichostemma eilhardi, p. 437 ; Zygonemertes virescens, p. 483 ; 

 Tetrastemma elegans, p. 431. 



