84 PROTOPLASM 



vesicles projecting beyond the edge, very sharp focussing 

 is not infrequently necessary, to recognise the excessively 

 thinned-out external wall of such foam vesicles. 



When Frommann applies the experience which he obtained 

 on drops with " non-fluid contents," with regard to the gaps 

 alleged to occur in the wall of the vacuoles, in order to 

 support his view of the net-like structure of protoplasm, he 

 would seem to forget that the latter is to a great extent fluid. 



Frommann also makes some communication upon the 

 phenomena of streaming in drops of foam, from which, how- 

 ever, I can only conclude that he never observed good 

 streaming movements. As far as I understand his com- 

 munications, all that he remarks upon this subject does not 

 refer at all to the drops of foam, but to the irregular 

 phenomena of streaming and movement, which are shown 

 by drops of a paste of oil and K C0. when transferred to 

 water. 



