Figs. 85-89. Nuclei from the small intestine of Necturus, contracted by 

 electrical stimulation. Fig. 85 is a completely relaxed nucleus. There is a 

 fine chromatin reticulum and ji single plasmasome (pi.). In Fig. 80 a nucleus 

 is shown, one end of which is just beginning to contract. The chromatin 

 has changed from a granular reticulum to fine longitudinal strands (a). 

 Fig. 87 shows the chromatin arranged in loops at one end of the nucleus. At 

 the same end the nuclear wall is serrated. Fig. 88 shows a festoon of thick 

 chromatin strands. In Fig. 89 is shown a completely contracted nucleus. 

 The heavy chromatin strands are arranged in festoons at either end (ch. f.). 

 The ends of the nucleus are serrated. Zenker's fluid. Iron-haematoxyliu. 

 X 1700. 



Figs. 90-92. Resting nuclei from muscle of intestine of Necturus kept for 

 20 minutes in 1 per cent cocaine solution. Zenker's fluid. Iron-htematoxylin. 

 X 1100. 



Figs. 93, 95. Contracted nuclei from muscle of the small intestine of 

 Necturus. The tissue was contracted by placing it in pilocarpine solution. 

 Zenker's fluid. Iron-hiiematoxylin. X HOO. 



Figs. 96-99. Nuclei from the same source as those shown in Figs. 93-95. 

 Instead of fixing the tissue frozen sections were made and stained in 

 methylene-blue. Figs. 96-98 are partially contracted nuclei. The chromatic 

 changes are marked. Fig. 99 is a completely contracted nucleus. Its struc- 

 ture is almost identical with that shown in Fig. 89— ch. f., chromatin festoon. 

 Frozen sections. Metliylene-blue. X 2200. 



