PROTOPLASM AND LIFE. 733 



of resisting the entrance of coloring matter into its substance. As 

 many here present are aware, microscopists are in the habit of using 

 in their investigations various coloring matters, such as solutions of 

 carmine. These act differently on the different tissues, staining some, 

 for example, more deeply than others, and thus enabling the histolo- 

 gist to detect certain elements of structure, which would otherwise re- 

 main unknown. Now, if a solution of carmine be brought into contact 

 with living protoplasm, this will remain, so long as it continues alive, 

 unaffected by the coloring matter. But if the protoplasm be killed, 

 the carmine will at once pervade its whole substance, and stain it 

 throughout with a color more intense than even that of the coloring- 

 solution itself. 



But no more illustrative example can be offered of the properties 

 of protoplasm as living matter, independently of any part it may take 

 in organization, than that presented by the MyxomycetcB. 



The MyxomycetcB constitute a group of remarkable organisms, 

 which, from their comparatively large size and their consisting, during 

 a great part of their lives, of naked protoplasm, have afforded a fine 

 field for research, and have become one of the chief sources from 

 which our knowledge of the nature and phenomena of protoplasm has 

 been derived. 



They have generally been associated by botanists with the fungi, 

 but though their affinities with these are perhaps closer than with any 

 other plants, they differ from them in so many points, especially in 

 their development, as to render this association untenable. They are 

 found in moist situations, growing on old tan or on moss, or decaying 

 leaves or rotten wood, over which they spread in the form of a net- 

 work of naked protoplasmic filaments, of a soft, creamy consistence, 

 and usually of a yellowish color. 



Under the microscope the filaments of the network exhibit active 

 spontaneous movements, which, in the larger branches, are visible un- 

 der an ordinary lens, or even by the naked eye. A succession of un- 

 dulations may then be noticed passing along the course of the threads. 

 Under higher magnifying powers a constant movement of granules 

 may be seen flowing along the threads, and streaming from branch to 

 branch of this wonderful network. Here and there offshoots of the 

 protoplasm are projected, and again withdrawn in the manner of the 

 pseudopodia of an Amoeba, while the whole organism may be occasion- 

 ally seen to abandon the support over which it had grown, and to 

 creep over neighboring surfaces, thus far resembling in all respects a 

 colossal ramified Amoeba. It is also curiously sensitive to light, and 

 may be sometimes found to have retreated during the day to the dark 

 side of the leaves, or into the recesses of the tan over which it had 

 been growing, and again to creep out on the approach of night. 



After a time there arise from the surface of this protoplasmic net 

 oval capsules or spore-cases, in which are contained the spores or repro- 



