136 INTRODUCTION TO CYTOLOGY 



must have entered from outside during the telophasic enlargement of the 

 nucleus. It is held by a number of investigators^ that this material is 

 primarily the spindle substance which has functioned during the preceding 

 stages. Although some have inclined to the view that the matrix and 

 the entering fluid remain distinct, it has also been commonly thought that 

 in such nuclei the two become intermingled to form karyolymph, new 

 matrix differentiating about the chromonemata again in the ensuing 

 prophase, when matrix and karyolymph are easily distinguishable.'' By 

 some investigators^ this has been interpreted as an actual impregnation of 

 the matrix by the other fluid, the metabolic nucleus thus consisting of 

 chromosomes swollen and in contact or even fused so far as their matrix is 

 concerned. Accordingly, in the prophase the matrix and the other fluid 

 again separate, the former condensing about the chromonemata and 



becoming chromatic as the latter accumulates between 

 the chromosomes in the form of future spindle sub- 

 stance. On this hypothesis, therefore, the karyolymph 

 of the metabolic nucleus is matrix plus spindle sub- 

 stance (" parachromosomic substance": Koerperich), 

 while in the advanced prophase it is the latter sub- 

 stance alone. On the other hand, the conditions 

 observed in Zea sporocytes (Fig. 65a) strongly suggest 

 Fig. 75.— Chro- the possibility that in nuclei generally the matrix may 

 Tmbr^J'^ofTtiS^Js'! maintain its identity from telophase to prophase in the 

 {After Richards, form of anastomoses, nucleolar matter, and possibly 

 ^^ ■-' thin sheaths about the chromonemata. 



Of considerable interest are those nuclei in which every chromosome 

 of the telophase group forms an individual vesicle, or karyomere.^ In 

 some cases the karyomeres may eventually fuse partially or completely, 

 but in others they remain separate although in contact, forming what is 

 virtually a group of small nuclei containing one chromosome each (Fig. 

 75). It is thus possible to think of chromosomes as bodies cooperating 

 with the cytoplasm somewhat after the manner of plastids,^ from which 

 they differ, however, in acting in highly organized groups of differentiated 

 individuals and undergoing a complicated series of changes during their 

 reproductive cycle. 



The nuclear membrane has usually been regarded as one which 

 forms, perhaps in the manner of a precipitation membrane,^ where the 

 3 E.g., de Litardigre (19216), Martens (19296), and Koerperich (1930). 

 ^ Kaufmann (1926a), Sharp (1929). 

 6 Martens (19296), Koerperich (1930). 



6 ConkUn (1901a) on Crepidula, Wenrich (1916) on Phrynotettix, Renter (1909) on 

 Pediculopsis, Richards (1917) on Fimdulus, Pinney (1918) on fish hybrids, Eisentraut 

 (1926) on Acridid(p, Heberer (1927) on Cijclops, B. G. Smith (1929) on Cryptobranchus. 

 ' Gregoire (1925, 1928). 

 8 Gates (1909a), Tischler (1921-1922). 



