PROTOPLASM. 365 



up of energy, but a transformation, a remolding of it in other and, 

 in the case under consideration, higher kinds. As the wide and rapid 

 vibrations which constitute the expansive power of steam are made, 

 by means of suitable mechanical appliances, to disappear in condensa- 

 tion and to reappear as locomotion, so the potential forces locked up 

 in the molecules of protoplasm appear in the breaking down, the de- 

 composition, of these molecules as spontaneous movements of some 

 portions of the mass. 



The energy expended in the movements of protoplasm is supplied 

 through the chemical changes going on in its substance, by the break- 

 ing down of compounds possessing much latent energy into more sim- 

 ple ones containing less such energy. 



These downward chemical changes are mainly processes of oxida- 

 tion, one of the chief products of oxidation being carbonic-acid gas. 

 Now, the taking in of oxygen and the giving out of carbonic acid 

 together constitute respiration ; hence protoplasm is " respiratory " 

 another of its vital properties. It breathes, as the fish does, by absorp- 

 tion of oxygen from its surrounding medium ; but it breathes at the 

 entire surface of its mass instead of at special parts of its surface, as 

 in the fish. This is true of vegetable as well as animal protoplasm, 

 the two being indeed regarded, in all essential points, as identical. 



Protoplasm is also " reproductive.'''' Haeckel, in his history of the 

 discovery of the monera, which consist of little globules of simple 

 protoplasm, describes their mode of reproduction as follows : " The 

 little creature divides into two halves, and each of these goes on living 

 like the original one." 



But there is a form of living protoplasm even more simple, if pos- 

 sible, than the moneron of Professor Haeckel the Myxomycetoe of 

 which a very good description may be found in the inaugural address 

 of Professor Allman, President of the British Association, in 1879, 

 published in the October number of " The Popular Science Monthly * 

 of that year. These organisms consist, during the greater part of 

 their lives, of simple protoplasm. They may be found in moist places 

 growing on decaying leaves, rotten wood, etc., etc., over which they 

 spread in the form of a net-work, exhibiting amoeboid movements, ap- 

 pearing to be sensitive to the light, and giving other evidences of life. 



But we may find a specimen of protoplasm even nearer home than 

 this. Prick your own fingers, if you choose ; withdraw a drop of liv- 

 ing blood from the wound, and, having properly diluted it, place it 

 under your own microscope for observation. Scattered among the 

 numerous small bodies which give to the blood its brilliant crimson 

 hue, may be seen a few somewhat larger colorless ones the leucocytes 

 or white cells. 



These microscopic bodies consist mainly of simple, undifferentiated 

 protoplasm. They* differ from the monera (first found by Haeckel 

 floating on the surface of the Mediterranean Sea) in being nucleated ; 



