226 First IMaturation Spindle of Allolobopliora Foetida 



matic cytoplasm, with the etl'ects of fixation on the two nuclear constitu- 

 ents, chromatin and achromatic nucleoplasm, for in both cases the reac- 

 tion to fixation is strikingly alike. Such a crude comparison is instruc- 

 tive only to illustrate the fact that both chromatin and archoplasm can 

 be identified after some fixatives and obliterated after others, yet the 

 specific character of chromatin is universally admitted, whereas the spe- 

 cific character of archoplasm has been very generally doubted. We do 

 not mean to imply that the two substances, archoplasm and achromatic 

 cytoplasm, are the sole constituents of the cytoplasm, any more than the 

 chromatin and achromatic nucleoplasm may be the sole constituents of 

 the nucleus. Archoplasm and achromatic cytoplasm are as much at the 

 mercy of the fixatives as are the chromatin and achromatic nucleoplasm, 

 and, like them, can be fused together into a network or into masses in 

 which the constituents are indistinguishable, or they may be so separated 

 that the two are readily differentiated. Such a differentiation is seen 

 in the unstained sections of Photos. 68 and 69, Plate IV, the chromatic 

 archoplasm and relatively achromatic cytoplasm being segregated into 

 quite definite areas. We do not claim that such pronounced cases of seg- 

 regations more nearly approximate the living condition, but they may be 

 instructive as an aid to demonstrating the individuality and continuity 

 of the substances during these stages, and the same may be said of some 

 forms of segregated chromatin shown in many of our photographs of sec- 

 tions. The achromatic cytoplasm of Photos. 10, Plate I, 68 and 69, Plate 

 IV, like the achromatic nucleoplasm, is a relatively homogeneous sub- 

 stance, but it becomes granular and chromatic when combined with the 

 archoplasm (Photo. 13, Plate I, just as does the achromatic nucleoplasm 

 when combined with chromatin (cf. the nucleoplasm of Photo. 34, Plate 

 II, with that of the germinal vesicles of Plates II, III, IV). Aggrega- 

 tions of archoplasm like the three shown in Photo. 13 are distributed 

 throughout the cytoplasm of the entire egg (cf. Foot and Strobell. '98, 

 Photo. -9). Such aggregations are typical of chromo-acetic preparations 

 and in the light of our recent study of the germinal vesicle we are 

 convinced that the entire cytoplasm of such preparations represents an 

 artificial combination of archoplasm and achromatic c3^toplasm compar- 

 able to the fusing of the chromatin and achromatic nucleoplasm in the 

 germinal vesicles of the same preparations (Photo. 34), and they support 

 the observations of the investigators who question the specific nature of 

 archoplasm. Such an interpretation would be supported also by Photo. 

 100, Plate VI, but a comparison of these two photographs (13 and 100) 

 with 68 and 69, Plate IV, suggests that the individuality of the archo- 

 plasm, so clearly shown in the last two photographs, is only obscui'cd 



