20 PROTOPLASM 



tion of C0 2 is indispensable for the success of the experi- 

 ments. 



Successfully prepared drops are, as has been said, com- 

 pletely round, and, as follows from this, quite fluid. In 

 transmitted light they appear of an even dark-yellowish 

 brown, which was usually a sign to me that the process had 

 taken a favourable course. They are permeated by coarse 

 drops of fluid or vacuoles in more or less abundance, while 

 their evenly frothy general substance is much too finely 

 structured for its composition to be recognised under these 

 conditions. On the surface of such drops there collect, as 

 a rule, more or fewer fine granular structures, which are 

 probably a hard, not easily dissolved soap. They are of no 

 importance when they do not appear in too great quantity, 

 since they can, for the most .part, be washed away by 

 a current of water. Were the oil too fluid, and hence 

 unsuitable, foam is not evenly formed throughout the whole 

 mass of the drop ; sometimes it is only full throughout 

 of larger drops of fluid, without being properly frothy, while 

 at other times, between finely frothy portions, there are 

 to be found more or less homogeneous portions of oil. Of 

 course these relations can only be made out with sufficient 

 distinctness when the drops are strongly compressed. 



Were the oil too much thickened it lost its fluidity in the 

 process, as follows from the fact that such drops did not 

 round themselves off, but retained more or less irregular contours. 

 Although I am not able to explain this phenomenon properly, I 

 must nevertheless call attention to it. It seems to show that on 

 thickening peculiar alterations in the oil take place which I am 

 not in a position to follow up further, but which, however, 

 are most important for the success of the experiment. If these 

 alterations exceed a certain measure, they prove harmful in turn. 

 As a proof, I may adduce the following. Very strongly thick- 

 ened and quite viscid cod-liver oil, rendered more fluid with 

 ordinary cod-liver oil, was made up into paste with K 2 C0 3 

 in the usual manner, and placed in water. At the com- 

 mencement the drop became quite finely frothy, but towards the 

 evening the foam had almost entirely broken up, and the next 

 morning had entirely vanished, all but a few very transparent drops 

 and some finely granular cloudy masses and threads. Also, the 

 froths manufactured from very viscid, thick olive oil, which had 



