362 LOUIS I. DUBLIN. 



are erythrophilous. In Pediccllina, at the stage of the formation 

 of these caps, the chromosomes are in the process of shortening 

 from long ragged threads to small thick rings and bars of the 

 first maturation mitosis, and it is evident that a considerable part 

 of their substance is lost during the change. Fig. 14, a, shows 

 very clearly the apposition of one of these long chromosomes to 

 the cap with the strong probability that the substance of the latter 

 is being increased at the expense of that of the former. 



As in Limax also, the nucleolus of the Pedicellina ovum plays 

 no observable part in the formation of the first polar figure. Its 

 structure, now much reduced, disintegrates and its remains are 

 cast out into the light area with which the spindle is surrounded. 



The facts observed appear to harmonize, in the main, with the 

 general conclusions which Hacker, '95, has reached. At no 

 period of egg-development is there any possibility for the origin 

 of chrornatin from the nucleoli. Indeed, the only perceptible 

 relation which it may have with the chromosomes, excepting 

 those obviously ascribable to accidental apposition, are those 

 where the former adds to its own substance from the cleavage 

 products of the latter. When the uncertain evidence of such 

 works as those of Guenther and Hartman, and the absolute denial 

 given by Hacker, '02, Miss King, '01, and Janssen, '04, to the 

 results of Carnoy and LeBrun, '97-'99, is considered, then it may 

 be concluded that the true nucleoli may, after all, be of one type, 

 and are to be distinguished from the undoubted chromatin bodies 

 such as those described by Blackman, '03, Wilson, 'oi, and others 

 which are but temporary aggregations of chromatin unwinding 

 the materials from which they are formed. 



It gives me great pleasure to acknowledge my indebtedness to 

 Prof. E. B. Wilson under whose observation this study was made. 



DEPARTMENT OF ZOOLOGY, COLUMBIA UNIVERSIIY, 

 January 6, 1905. 



