No. 2.] COMPARATIVE CYTOLOGICAL STUDIES. 469 



of the first pole spindle (Fig. 311) lie twelve small chromosomes, 

 which stain an intense blue black with haematoxylin and have 

 an oval or slightly elongate form. It remains for investigators 

 working with more abundant material and with stronger micro- 

 scopical lenses, to penetrate more deeply into these phenomena 

 of the chromatin changes, but it would seem that the chromo- 

 somes of the first pole spindle have the value of either tetrads 

 or dyads. The lilac or even reddish stain of the chromatin at 

 a particular period would seem at first sight to be due to the 

 assimilation by the chromatin of that nucleolar substance dif- 

 fused in the nuclear sap ; but even as probably it might be due 

 to the mere penetration of this substance between the individ- 

 ual microsomes of each chromatin thread, without any chemical 

 change of the chromatin substance (Fig. 309). The red- 

 staining globules in the nuclear sap, which I have assumed 

 to be of nucleolar derivation, cannot be considered as meta- 

 morphosed portions of chromatin substance, since they vary 

 so considerably in size and number ; this point needs to be 

 emphasized, since in some of the larger germinal vesicles no 

 trace of chromatin is to be seen, and it might be thought by 

 some one that these globules, which occur in such nuclei, repre- 

 sented the supposedly absent chromatin. (Platner, '89c, had, 

 in Aidastommn seen only nucleolar fragments and overlooked 

 the true chromosomes.) Where in the largest germinal vesi- 

 cles, before the formation of the pole spindle, the chromatin 

 appears to be absent in the nucleus, we must assume that it 

 is merely obscured by the large amount of diffused nucleolar 

 substance. 



In the first pole spindle (Fig. 311), after treatment with 

 Flemming's fluid or with corrosive sublimate, the mantle fibers 

 have a remarkable thickness and appear even thicker than in 

 Fig. 311; they stain a reddish-lilac color with the haematoxylin 

 and eosin stain, not a lilac blue, as do the rays of the asters 

 and the cytoplasm ; I could not determine whether they extend 

 quite to the centrosomes. I am also unable to decide whether 

 each chromosome lies upon a single spindle fiber which extends 

 from centrosome to centrosome, or whether its ends are con- 

 nected with separate fibers. The centrosomes are rather large. 



