112 PROTOPLASM 



that layers of protoplasm of such thinness, as are formed here 

 and there by the plasmodia of Myxomycetes, are objects especi- 

 ally suited for investigation. In order to obtain a, good pre- 

 paration, it is best to proceed as follows. Some slides are 

 thoroughly wetted and placed upon the tan, which should 

 be in a large damp chamber in the dark. It is then neces- 

 sary to wait until some plasmodia creep on to the slide and 

 have spread themselves out in a very fine layer. Of course, 

 only the thinnest and most branched networks should be chosen 

 for preparations. Or, on the other hand, plasmodia which are 

 creeping about on the walls of the vessel, or elsewhere, can be 

 simply scraped up with a scalpel, and the lumps of protoplasm 

 kept on damp slides in a damp chamber in the dark. I found 

 almost always that after about twenty-four hours, such lumps 

 of protoplasm had spread themselves out again into very 

 beautiful networks. It is now only necessary to keep the slide 

 in question for some time in a vertical position within a damp 

 chamber, so that the superfluous water may run off as far as 

 possible, and then to transfer it to picro-sulphuric-osmic acid or 

 some other fixing fluid. When the water has been as far as 

 possible removed from the slide in the manner stated, without, 

 however, the plasmodium being dried up, the latter, after fixation, 

 adheres quite firmly to the glass. If too much water has 

 been left behind, the plasmodial network easily separates of}', 

 which renders further preparation very difficult. Plasmodia that 

 are adhering well can, after fixation, be played upon by a strong 

 spray from a flask without becoming loosened. Of course the 

 preparations can be stained as desired, but all the observations 

 described in the following were made upon unstained plasmodia, 

 which after being washed were put up in water. 



In such preparations the alveolar structure of the protoplasm, 

 as I have often described it above, can be seen most beautifully. 

 In the plasmodial network places may be found of such thinness 

 that they are only formed of a single layer of alveoli. Places of 

 this kind are of course especially suited for study, and show all 

 the phenomena which we have observed above in similar thin 

 layers of oil-lather. Without entering into a detailed descrip- 

 tion, I refer to the Photographs XV. and XVI., XVII., and 

 XVIII. and XIX. Photograph XV. shows a small lobed projec- 

 tion at the edge of a plasmodium, which in the' prepara- 

 tion is torn across close to its origin, probably because the 

 principal mass, from which it arose, contracted strongly. In 

 as accurate a focus as possible, such as was chosen in Photo- 

 graph XV., the frothy framework is distinctly noticeable in 

 the whole of the internal and thicker portion of the lobe. The 



