OlTOLOaiCAL CHANGES PRODUCED IN DU08ERA. 219 



reticulum of threads, staining blue, purple, or red. The 

 nucleus has almost lost its identity, having amalgamated with 

 its surrounding cytoplasm to form a more or less crescentic 

 body, which stains reddish purple, and exhibits no differentia- 

 tion whatever. 



Summary. 



1. By feeding with chemically different foods very cha- 

 racteristic alterations are obtained, both in the colour re- 

 action and morphology of the cell. For example, in five 

 seconds white of egg causes both the cytoplasm and nuclear 

 plasm to become more eosinophilej while pure amphopeptone 

 increases their affinity for blue stains. The former food quickly 

 causes great impoverishment of cytoplasm and nuclear plasm, 

 while the first effects of pure peptone are to increase their 

 bulk and density. Both the foods produce an enormous in- 

 crease of the chromatin element of the nucleus, while other 

 foods, e. g. nucleic and nucleic acid, produce no such result. 



2. While the cytoplasm is the cell constituent most rapidly 

 and most constantly affected by external stimuli, the nucleus 

 is the seat of metabolic activity, and the state of the nuclear 

 organs indicates whether or not the food supply was of service 

 to the metabolism of the plant. 



It is not surprising, therefore, to find a certain independence 

 of cytoplasm and nucleus in their behaviour to external 

 stimuli, coupled with great interdependence with respect to 

 all resulting processes of metabolism. Thus, substances such 

 as paraffin and nucleic acid act merely as stimuli to the secre- 

 tive activity of the cells; and they cannot be regarded as 

 foods, for they affect the nucleus only by causing a slight 

 drainage on the nuclear plasm and nucleolus. If the stimulus 

 is very transient the nucleus remains unaffected. On the 

 other hand, with highly nutritious food like egg-albumin and 

 peptone the nucleus is the seat of the greatest change, and 

 the chromosomes, i. e. the nuclein, undergo an enormous 



