46 ANDREWS. 



ness, yet in t'nem a true structure has been found, and one under- 

 going such modifications as are found in the coarser structures. 

 It is necessary to distinguish between visibility of areas and 

 visibility of the protoplasm proper, or continuous substance, for 

 the character of its inclusions may make a whole area distinct 

 or prominent, while its protoplasm proper may at the same time 

 be very fluid and not so readily seen as that of adjacent areas 

 which in toto are less conspicuous ; but the optical phenomena 

 in such cases are markedly different from those in which areal 

 visibility is due to quality of the continuous substance. 



[46] I would group all areas having the origin and character 

 of the ectosarc of protoplasts under the head of ectosarcal 

 formations or modifications of the substance. As stated above, 

 all physiological pellicles fall naturally into this group. 



To glance for a moment at the formation of ectosarc by 

 Amoeba may enable the reader better to understand the argu- 

 ment. The point involved is of radical importance. An 

 Amoeba proteus is at all times covered by a variably thick, 

 hyaline layer, whose surface forms an unstable pellicular mem- 

 brane. But when at times, in the heave and flow and evanescent 

 shiftings of the protoplasm, there is at any point a rush of sub- 

 stance that wholly or partially pushes, or breaks through, this 

 layer or is yielded to by it, so as to come in more or less close 

 proximity to the water, the phenomena may be said to represent 

 to some extent a primitive formation of ectosarc. This may 

 have been primitively a purely physical incident, taken advan- 

 tage of by, or necessarily causing physiological or physical 

 vantage for, the living substance.-^ 



One does not, however, see the whole mass covered at any 

 one moment by such an area ; that has been the work of ages, 

 and the present habit, while typifying a more primitive act, is 

 of course a much modified and extended form of it, for in the 

 simplest Amoeba known, the plastic substance is already very 

 old and full of registered experience. 



Watching an initial formation, not a mere displacement, of 

 ectosarc, one sees a gradual, or more or less sudden, or even a 

 spurting, outflow of what has been called the hyaloplasm of the 



1 See New Structural Formula. 



