No. 3.] EGG OF ALLOLOBOPHORA FCETIDA. 



525 



and the parts become Jiomoge7ieoiis in appearance and then 

 enlarge to form the great yolk-plates,'' p. 228. ^ In Allolo- 

 bophora the yolk-nucleus substance retains its granular form 

 at this stage and shows the same chemical reaction. In view 

 of Calkins's text the bodies in question can be compared only 

 to the mass of osmophile substance of Photo 45, PI. XLII, or 

 to a pathological condition which is less usual, in which dense 

 homogeneous chromatophile masses are scattered throughout 

 the cytoplasm (Foot (9)). Photo Zj, PL XLV, is a repro- 

 duction of Calkins's Fig. 4, which he describes as "later 

 stage of disintegration." Wilson applies this interpretation 

 to Calkins's Fig. 5 (Photo Z^, PI. XLV), Calkins himself 

 describing this as a "nearly ripe ^gg showing yolk-plates." 

 If his interpretation of these bodies is correct, they should be 

 found in later stages of the ^gg, i.e., during its maturation, 

 its fertilization, and in the mature (ripe) &gg. This is not the 

 case, however, for Allolobophora. In normal eggs there is 

 nothing that can be interpreted as the "great yolk-plates" 

 which Calkins describes for Lumbricus. 



Origin of the Yolk-Nucleus (Archoplasm). 



The weight of authority is in favor of a nuclear origin. In 

 the Qg'g of Allolobophora we have been unable to discover any 

 decisive evidence on this point, and we must therefore retain 

 the neutral attitude taken in an earlier paper of avoiding any 

 assumption as to its origin, evidence being given to show only 

 that it was neither of chromatin nor nucleolar substance. It 

 is first seen close to the nuclear wall, and this proximity to 

 the nucleus is the only evidence we can discover in favor of 

 a nuclear origin. The fact that in such small cells as those 

 shown in Photos i, 3, and 6, PI. XLI, there is no continuity 

 between the yolk-nucleus and any nuclear constituent is the 

 sole evidence we have of a cytoplasmic origin.^ 



1 Italics are ours. 



2 We call attention to this here because in spite of the care taken to empha- 

 size these points in an earlier paper (9) they have been misinterpreted. Crampton 

 (6), p. 47, says : " Foot asserts that the appearances described by Calkins are 

 pathological, that in Allolobophora the yolk-nucleus is of cytoplasmic origin, 



