324 DR. E. KLEIN. 



or artificial) of the fibres of the intranuclear network. The 

 observations of Van Beueden, O. Her twig, Schwalbe, 

 Langhans, Flemming himself, and last, not least, Auerbach 

 and Eimer, appear to me to lend support to the view that 

 in most cells tlie so-called nucleoli are local accumulations of 

 the intranuclear network, that they are inconstant in size and 

 number, and that they are only transitory appearances. As 

 regards this last point, the observations of Strassburger, 

 Schwalbe and Langhans, may be here referred to, especially 

 Langhans (1. c), according to whom the single nucleolus or 

 multiple nucleoli met with in the nuclei of cells of the 

 human decidua serotina, are the result of the shrinking of 

 the network. 



The assertions that have been made as regards sponta- 

 enous movements of nucleoli (Auerbach,^ Brandt,- Eimer, ^ 

 Kidd,*^ and others) are quite compatible with the above 

 view, for E. van Beneden, as previously mentioned, has 

 observed movements in the intranuclear network, and it is 

 quite possible that the above assertions might refer to con- 

 tractions of part of the network. 



A last point to be considered is the nuclear membrane in 

 it relation to the intranuclear network. I shall have to 

 mention this more fully hereafter in connection with the 

 cell-substance itself, but ^vill limit myself here only to say 

 that the examination of the nuclei in my specimens, 

 especially of nuclei that are isolated, and whose limiting 

 membrane has become broken at one place or another (see 

 fig. 8, PI. XVI), shows that what usually appears as nuclear 

 membrane is composed of an outer thicker portion, which 

 is the limiting membrane proper, and — closely connected with 

 it — of an inner, more or less incomplete — probably because 

 reticular — delicate layer, which is, properly speaking, a peri- 

 pheral condensation of the intranuclear network, with which 

 it is, of course, connected by longer or shorter threads. 

 The clear space which may be observed in some instances 

 between the ' membrane ' of the nucleus and the intra- 

 nuclear network is due, us mentioned on a former page, to a 

 retraction of the latter from the former, and is a space, not 

 between the two layers of the limiting membrane, but 

 between the inner layer of this and the bulk of the intra- 

 nuclear network. 



2. The following forms of cells present themselves in our 



' ' Organologisclic Studicn,' &c., Abth. .S, Breslau, 1S74. 

 2 ' Arcbiv. f. JMikr. Aiiatom.,' lid. x. 

 • ' Archiv. f. Mikr. Auat.,' Bd. xi. 

 < This Journal, 1875. 



