50 



ANDREWS. 



It is important to remember that in the living substance true 

 ectosarcal layers are formed at any depth and in any relative 

 position and of any form, as readily as they arise externally to 

 masses ; and that such formation may be the work of a moment 

 only. 



[47] Ectosarcal formations often arise by outflow of the 

 interalveolar substance alone without implicating or even visibly 

 disturbing an existing structure of Biitschli.^ 



[48] All ectosarcal formations appear to be essentially organ- 

 izations of the continuous element involving redistributions of 

 the alveolar inclusions ; and to be formed for physiological func- 

 tion ; for organized reaction of the substance as such in its own 

 character to environment. 



[49] In many areas so formed it seems to be of no moment 

 which portion of the continuous element is in contact with 

 any visible vesicle, but all portions can react alike near all 

 portions of the general inclusion fluid. In other words, there 

 is in such areas a homogeneousness of the continuous element 

 and equal homogeneousness in general character of its spe- 

 cific stimuli. Any part of such areas is, therefore, for the 

 time being physiologically equal to any other part in these 

 respects. 



(a) Yet any part of the area may show specific differences 

 of action, which are secondarily referable to either local differ- 

 ences in its own finer structure, or inclusions, or slight 

 differences in kind of the inclusions of the given structure. 

 Such local specific activities are always directly referable to 

 characteristic changes of the continuous element. 



[50] Although true protoplastic ectosarc, as it is best known, 

 is commonly seen as arising in response to contact with external 

 environment, it may hardly be thought that such areas are in 

 general a result of such contact, for in the majority of cases 

 they are formed before, often long before, the occasion of their 

 use. Sometimes they may never even reach that environment 

 for reaction to which they have been moulded. In the forma- 

 tion internally to a Protozoan's mass of pellicles and pellicular 

 organs which, till after completion, are shut out from their 



^ See Activities. 



