CYTOLOGICAL OHANflES PRODUCED IN DROSERA. 205 



Chromosomes are the organs which show the well-knowa 

 affinity for alkaline dyes. They are situated at the periphery 

 of the nucleus, and consist of nuclein. 



Nuclear plasm is the material which, in the resting state, 

 forms the main bulk of the nucleus. It is neutrophile in 

 character, and is frequently called the nuclear sap, but corre- 

 sponds to " oedematin " globules. 



Nuclear sap is the more watery fluid inside the nucleus, in 

 which is suspended the nuclear plasm, the latter being pre- 

 cipitable by HgCL, and otlier reagents. 



Nucleoli are the spherical organs which show a special 

 affinity for acid dyes, and have a more or less central position, 

 and they consist of Flemraing's paranuclein. 



Resting Gland Cells (fig. 1). — The gland cells in their 

 resting state, when fixed and stained by Mann's methods, 

 appear as follows : 



The cell wall is pale blue ; the cytoplasm is arranged in an 

 open foam-like manner; it stains pure blue with a coarse 

 granulation embedded in it, which appears of a deeper blue 

 and represents the zymogen. 



The nucleus is situated just below the middle of the cell. 

 It may be spherical or oval. It stains purplish, and is sharply 

 defined against the cytoplasm, partly because of the difference 

 in tint, and also because of the peripherally placed, very 

 minute, dark blue chromosomes. 



The nuclear plasm is granular, always very dense, and of a 

 purplish tint. One (sometimes more) very distinct, deep red 

 nucleolus is always present, surrounded by a narrow Frora- 

 raann's clear zone. 



Experiments. 



Paraffin (fig. 2). — The rapid changes which can be pro- 

 duced by certain foods suggested the idea of ascertaining 

 whether purely physical factors, such as contact with insoluble 

 substances, would not also produce effects. When pieces of 

 well-boiled cork were applied to the leaves vacuolation of the 



