284 A NOTE ON ADSORPTION [ch. 



the liquid, it may be quickly caused to disappear by the presence 

 in its neighbourhood of some substance capable of reducing the 

 surface tension ; for this substance, being adsorbed, may displace 

 from the adsorptive layer a material to which was due the rigidity 

 of the film. In this way a "bathytonic" substance such as ether 

 causes most foams to subside, and the pouring oil on troubled 

 waters not only stills the waves but still more quickly dissipates 

 the foam of the breakers. The process of breaking up an alveolar 

 network, such as occurs at a certain stage in the nuclear division 

 of the cell, may perhaps be ascribed in part to such a cause, as 

 well as to the direct lowering of surface tension by electrical 

 agency. 



Our last illustration has led us back to the subject of a previous 

 chapter, namely to the visible configuration of the interior of the 

 cell; and in connection with this wide subject there are many 

 phenomena on which light is apparently thrown by our knowledge 

 of adsorption, and of which we took little or no account in our 

 former discussion. One of these phenomena is that visible or 

 concrete "polarity," which we have already seen to be in some way 

 associated with a dynamical polarity of the cell. 



This morphological polarity may be of a very simple kind, as 

 when, in an epithelial cell, it is manifested by the outward shape 

 of the elongated or columnar cell itself, by the essential difference 

 between its free surface and its attached base, or by the presence 

 in the neighbourhood of the former of mucous or other products 

 of the cell's activity. But in a great many cases, this "polarised" 

 symmetry is supplemented by the presence of various fibrillae, or 

 of linear arrangements of particles, which in the elongated or 

 "monopolar" cell run parallel with its axis, and which tend to 

 a radial arrangement in the more or less rounded or spherical 

 cell. Of late years especially, an immense importance has been 

 attached to these various linear or fibrillar arrangements, as they 

 occur {after staining) in the cell-substance of intestinal epithelium, 

 of spermatocytes, of ganglion cells, and most abundantly and 

 most frequently of all in gland cells. Various functions, which 

 seem somewhat arbitrarily chosen, have been assigned, and many 

 hard names given to them ; for these structures now include your 

 mitochondria and your chondriokonts (both of these being varieties 



