352 THOS. H. MONTGOMERY, 



unequally, and not simultaneously in its different parts, all possible 

 movements of the chromatin could thereby be produced ; but this 

 would demand differentiations of function in different portions of the 

 linin spirem, and I see no reason for assuming such differentiation. 

 Accordingly I would conclude that most of the movements of the 

 chromatin are phenomena automatic on its part, probably motions of 

 a flowing nature. And here it must be kept in mind that the chro- 

 matin is not made up of solid microsomes, but has a more or less 

 thickly fluid consistency, so that a flowing on its part is quite possible. 

 Apparently the fluidity is a viscidity. But though the linin spirem 

 would not seem to be in itself contractile or expansive, but rather a 

 path for the chromatin, this does not exclude the secondary linin 

 fibrils from being contractile; and since in Peripaius in the synapsis 

 these first appear about the time of the longitudinal splitting of these 

 chromosomes, since they connect chromatin granules of different 

 chromosomes, and since they appear thickest when the longitudinal 

 split of the chromosomes is widest, it would seem quite possible that 

 they may be the active agents in this splitting. And since these fibres 

 connect also the chromatin with the nuclear membrane, it could well 

 be by their contraction that in the prophases of mitosis the chromo- 

 somes are pulled to the periphery of the nucleus. 



3. The Polarity of the Nucleus and Cell Body. 



In Peripatus, from the stage of the last spermatogonic division 

 on, the nucleus shows a distinct polarity (Plate 25, diagrams 260, 261) ; 

 the angles (central ends) of the bivalent chromosomes are directed 

 towards one pole of the nucleus (where the pole of the spindle pre- 

 viously was, my central pole, Rabl's Polseite) ; while their open distal 

 ends are directed towards the opposite pole (my distal pole, Gegen- 

 polseite of Rabl) 1). 



There is also in Peripatus a distinct polarity of the cell body 

 (diagram 261, Plate 25): the pole with a small amount of cytoplasm 



1) Rabl (1885) is the one who has given most attention to the 

 polarity in the arrangement of the chromosomes, and from the per- 

 sistence of the polarity he argued very ably to a persistence of the 

 chromosomes. Carnoy (1885) found it well shown in the spermato- 

 cytes of Arachnids, independently of Rabl. Among others who have 

 paid attention to it may be mentioned Elemming (1887), Boveei (1888, 

 1890), Van Beneden & Next (1887), Heidbnhain (1892), v. Eelanger 

 (1896), Erancotte (1898), Kingsbury (1899), Eisen (1900). 



