1/2 M. LOUISE NICHOLS. 



both, forms the karyosphere. Possibly this might be regarded 

 as a continuation and exaggeration of the synaptic condition, 

 and, if this were true, a series of consecutive stages might be con- 

 ceived between the typical synapsis and post-synapsis of most 

 animals and plants and the extreme conditions presented by 

 Sarracenia. 



In the echinoderms, in MHS and in Euchroma a similar ten- 

 dency to condense reappears and in the germ cells later than 

 synapsis, owing, no doubt, to a chemical condition of the nu- 

 cleus varying from the usual type. Here there is in one case 

 (Euchroma) a more rapid condensation of chromatin than of linin 

 and a consequent partial separation, while in the other (Mus, 

 echinoderms) no such separation is apparent, chromatin and linin 

 condensing simultaneously (Plate III., Figs. 4 and 5). 



There is, however, little reason to believe that the difference 

 in the method of formation of the spermatocytic chromosomes 

 of Euchroma and most others insects is fundamental. The 

 gradual change in coloration as resting chromatin becomes 

 active goes to show that there is a chemical change in progress 

 from less acid to more acid condition, accompanied by a conden- 

 sation of substance. According to the differing constitution 

 of different nuclei, this chemical activity might be confined to 

 one center or distributed through the nucleus around several 

 centers. If the latter were the case, the network of resting 

 spermatocytes would break at various points and, condensing, 

 form the chromosomes, but if there were but one center, the 

 condensation would occur within a more circumscribed area. 

 In Euchroma, while the latter method is more common, it may 

 happen that the centers of condensation are multiplied (Fig. 15). 



An interesting question concerning the relation of the chemistry 

 of the nucleus to the individuality of the chromosomes presents 

 itself at this point. If it be true that the aggregation of chro- 

 matin is accompanied by a decomposition of nucleo-proteids 

 and a reduction of chromatin to nucleic acid or a simple com- 

 pound of that acid and also true' that the chromatin may be 

 separated from the linin and gathered into a karyosphere, may 

 it not be possible that the linin network is not homogeneous as 

 regards its chemical character, but that in different areas are 



