524 FOOT AND STROBELL. [Vol. XVII. 



but their chemical reaction is quite different, for Crampton 

 finds in Molgula that "the chemical reaction of the yolk- 

 spheres to dyes and other tests are precisely the same'^ as 

 those of the disintegrating yolk-matrix " ^ (6), p. 42. 



An examination of the unstained preparations of Allolo- 

 bophora (PI. XLII) will show that the chemical reaction of 

 the deutoplasmic (osmophile) granules is very different from 

 that of the yolk-nucleus. The latter fails to blacken with 

 osmic acid, even after many hours' immersion in a one per 

 cent solution, whereas an immersion of fifteen or even five 

 minutes is sufficient to blacken the osmophile granules. The 

 yolk-nucleus invariably stains intensely with haematoxylin, while 

 the osmophile granules very rarely react to this stain. 



The homogeneous masses of osmophile substance (Photo 

 45, PI. XLII), indicative of a pathological condition, suggest 

 the " great yolk-plates " of Lumbricus (Calkins (3)). As stated 

 in an earlier paper (9), "in normal eggs I find no structures 

 answering to the ' great yolk-plates ' described and figured 

 by Calkins for Lumbricus." In his book on the cell, Wil- 

 son (31) reproduces Calkins's figures, and in his last edition 

 (1900) describes Calkins's "great yolk-plates" as "fragmenta- 

 tion of yolk-nucleus." Is this a correction of Calkins's inter- 

 pretation } If this can be supported by a further correction 

 of Calkins's microchemical analysis and of his assertion that 

 these bodies are "great yolk-plates," " homogeneous" in appear- 

 ance, and not granular, like the yolk-nucleus, then Calkins's 

 Fig. 5 (see reproduction. Photo ZZ, PI. XLV) might be inter- 

 preted as representing a fragmentation of the yolk-nucleus, 

 and thus be compared to our Photos 19, 21, or 23, PI. XLI. 

 Calkins's (3) text, however, prohibits this comparison. "Next 

 the disintegrating masses lose their granular structure and 

 become large and homogeneous, forming the yolk-plates of the 

 Qgg," p. 226. " In Lumbricus the yolk-nucleus disintegrates 



^ The italics are ours. 



2 Their similarity in response to dyes seems to have one exception. " Corro- 

 sive sublimate affected the yolk so that it retains the iron-haematoxylin," p. 30. 

 " It is important to note that the yolk-matrix fails to stain with the haema- 

 toxylin," p. 32. 



