PROTOPLASM OF AMCEB& 107 



the nucleus. A so-called ectoplasm of hyaline, apparently 

 structureless consistency, is not, as I have already pointed 

 out, by any means always present, but may be wanting in 

 places or altogether ; thus it was not to be found occasion- 

 ally in the large A. proteus, nor as a rule in A. Umax. 

 Since, however, in A. proteus it was not infrequently beauti- 

 fully distinct in places, and since also the pseudopodia of 

 this Amoeba usually showed, at least towards the end, the 

 character of such hyaline protoplasm, it seems to me to 

 follow beyond a doubt that the hyaline ectoplasm arises 

 here, as in Gfromia Dujardini just described, by modification 

 from protoplasm with meshed structure, and can also be con- 

 verted into the same again. The surface of ' the body, 

 whether formed of hyaline ectoplasm or of protoplasm 

 structurally composed of a distinct meshwork, always shows 

 a relatively thick and dark limiting border, which has the 

 appearance of a pellicle both in living and prepared speci- 

 mens. This border can also be traced in the pseudopodia, 

 becoming more delicate and pale towards their attenuated 

 extremities. Under the pellicle -like margin there runs a 

 clear narrow zone on which the reticular meshwork of the 

 protoplasm borders directly,- when a hyaline ectoplasm is 

 not developed. The pellicle-like limiting border, together 

 with the narrow clear zone, present exactly the appearance 

 of a marginal alveolar layer. I have no doubt that they 

 represent one everywhere, and do not depend in any way 

 on optical relations. But as yet I have not been able to 

 convince myself with certainty in living Amoebae as to the 

 radial striation of this marginal alveolar layer. On the 

 other hand, I was frequently well able to do so, I may 

 remark, in specimens preserved with picro-sulphuric-osmic 

 acid mixture or even with iodine - alcohol. On Plate 

 IV. Fig. 4 the radially striated marginal alveolar layer can 

 be seen very plainly in an A. actinophora Auerbach, be- 

 neath the similarly striated envelope here present, upon 

 which I shall have a few words to add later. That the 

 radially striated envelope itself does not represent the real 

 marginal layer of alveoli, follows from the fact that it is very 

 clear and pale, and that the marginal alveolar layer proper 



