448 THE AMERICAN NATURALIST. [Vol. XXXVIII. 



The chromosomes come to lie in a vacuole (Fig. 7 c, d, e) con- 

 taining nuclear sap and later the chromatin becomes distributed 

 over a linin network and one or more nucleoli develop (Fig. 

 7 /> S)- ^^ was stated in Section I, the nuclear membrane 

 probably represents the reaction of the granular kinoplasm to a 

 fluid secretion around the chromosomes which becomes the 

 nuclear sap (La wson, :03a). However, the nuclear membrane 

 is generally a definitely organized film, much more sharply 

 defined than vacuolar membranes. The development of the 

 linin network is not well understood. It is readily seen that 

 the chromosomes become joined end to end and sometimes elon- 

 gate. The amount of chromatin diminishes as the linin substance 

 appears, but it is not certain whether the chromatin is changed 

 directly into linin, or whether the latter substance is a secretion. 

 The best evidence rather favors the former view. Nucleoli are 

 also believed to hold a very close chemical relation to chromatin. 



It is uncertain whether or not the chromosomes lose their 

 organic identity in the daughter nuclei. Investigations on this 

 problem are surrounded by many difficulties. It has been 

 claimed by Guignard ('99) for Naias and Strasburger (: 00) for 

 several forms that the chromosomes may be followed with cer- 

 tainty through the period between the first and second mitosis 

 in the spore mother cell. But other investigators have not been 

 able to trace the chromosomes after telophase and are inclined 

 to believe that the chromosome completely loses its identity in 

 the resting nucleus. One of the last investigations of Lilium 

 (Mottier, : 03) argues strongly for the latter view, and all who 

 have followed nuclei from one mitosis into another know that 

 the resting nucleus with its linin network and the granular 

 chromatin present conditions that generally make the recognition 

 of chromosomes impossible with the instruments and technique 

 at our command, but this does not prove that they may not be 

 present. 



The theory of the permanence of the chromosome has met 

 with much favor because it is argued that otherwise how could 

 the number be maintained so regularly through immense num- 

 bers of mitoses. But it can hardly be said that the doctrine is 

 estabhshed. It has also found favor because all the events of 



