82 ANDREWS. 



areas of ectosarc, the rush of substance transforming itself 

 here as rapidly as when close to the water. 



That ectosarc is not altogether a mere physical redistribution 

 of the elements, but has reference to physical organization of 

 these for physiological function, is manifest when one studies 

 a transformation of ordinary, irregularly structured, endosarc 

 into beautifully organized and uniform ectosarcal areas, in which 

 are then seen organized contractile activities. Such phenomena 

 can be followed from moment to moment in Amceba radiosa, 

 where the endosarc can be seen to transform itself in a short 

 time into ectosarc of mixed structure ; this to pass into a mani- 

 festly organized state, and then into contractile states, in which 

 all structure may or may not disappear from sight, the substance 

 becoming so dense and refractive as to fairly glitter, and so 

 resistant that when it has the form of long lash-like extensions 

 they may be bent elastically by pressure as if they were bristles, 

 and then in another moment will lash themselves about like the 

 flagella of Hetei-omita ox ^q^Y^q. the pseudopodia oi A.proteiis. 

 In such viscous states in A. radiosa when a posterior mass has 

 a thick ectosarcal covering, I have seen this thrown by contrac- 

 tion into folds which were so refractive as to simulate quite 

 well spiculae of flint, and by these contractions the whole mass, 

 including an anterior, film-like, ectosarcal flow, seemed to be 

 urged forward. In another moment the creature was a large 

 fan-shaped film of protoplasm, so delicate as to be scarcely 

 visible, preceding a protean, partially naked, lump of somewhat 

 filose endosarc. 



In addition to the facts cited and others of kindred import, 

 negation to any explanation of cleavage by surface tension was 

 had early in the summer of 1893 by the following experiment. 

 A starfish ^gg in the two-celled stage was gradually compressed 

 until the pellicular wall was broken and the peripheral proto- 

 plasm exuded at points from both cells, forming very short 

 blunt processes. Little by little these were augmented by 

 outflow of hyaline interalveolar substance, and at the same time 

 they showed local changes in structure, and amoeboid activities, 

 the substance flowing here and there and spreading itself out 

 over the surface of the whole ^gg. There seemed to be a 



