The spermatogenesis of Peripatus (Peripatopsis) balfouri. 347 



monaster stage the nuclear membrane disappears the distal linin 

 threads become the mantle fibres of the spindle, and the central 

 threads the connective fibres, so that here occurs for the first time a 

 segmenting of the linin spirem. 



This is a very brief summary of my observations on the per- 

 sisting relations of the linin and chromatin in Peripatus. The only 

 gaps in the observations were that the relation of the linin could not 

 be clearly observed in the metakinesis of the spermatogonia ; and that 

 in the following anaphases the distal linin threads could not be well 

 determined. All other changes were actually observed; and what 

 could not be seen owing to the great difficulties in studying these 

 delicate structures, was deduced from a comparison of earlier and 

 later stages. 



Accordingly in Peripatus there would seem to be a continuous 

 linin spirem present in all stages continuously from the prophase of 

 the last spermatogonic division, through the rest stage of the spermato- 

 cytes, up to the monaster of the 1st maturation division. The pre- 

 sence of such a persisting continuous linin spirem furnishes an ex- 

 planation for some phenomena which have been hitherto not satis- 

 factorily understood ^). 



1) Here may be recalled certain observations of other workers, 

 corroborative of my conclusions. Perhaps the most conclusive case of 

 the persistence of a linin spirem in a rest stage, is that of the salivary 

 glands of Chironomus, first made known by Balbiani (1881), and later 

 by FLEMMixa (1882), Leydig (1883), Korschelt (1884) and Macallum 

 (1895). Then the observations of Carnot (1885): according to him the 

 element nucléinien in Arthropods "est celle d'un boyau ou d'un filament 

 continu et pelotonné dont les circonvolutions, plus ou moins nombreuses, 

 sont répandues dans tout le noyau" ; and he states that the linin (his 

 plastin) remains continuous even when the chromatin segments into 

 rods. By dissolving out the chromatin he found that this spirem is 

 formed of an outer layer of linin (plastin) surrounding the chromatin 

 (nucléine). Van Beneden & Neyt (1887) described a continuous spirem 

 in the resting pronucleus of Ascaris. And Van Beneden (1883) shows 

 that in the prophase of the 1st cleavage spindle of Ascaris, after the 

 chromosomes are segmented from one another, and after the disappearance 

 of the nuclear membrane, chains ("trainees") of achromatic globules are 

 found, and that "les plus apparentes de ces trainees se montrent toujours 

 dans la prolongation des filaments chromatiques", and therefore would 

 seem to be parts of a persisting linin spirem. Van Beneden stated 

 very clearl}^ that "les cordons chromatiques possèdent une charpente 

 achromatique et que ce stroma .... peut abandonner cette substance 

 chromophile". Bovebi (1888) noted persisting inter-chromosomal fibres 

 ("secundäre Brücken"), as well as the axial fibres ("primäre Brücken") 



