2 BEPOET — 1879. 



able facts, and the justification of many significant generalisations. I 

 propose, in short, to give you in as untechnical a form as possible some 

 account of the most generalised expression of living matter, and of the 

 results of the more recent researches into its nature and phenomena. 



More than forty years have now passed away since the French natu- 

 ralist Dujardin drew attention to the fact that the bodies of some of the 

 lowest members of the animal kingdom consist of a structureless, semi- 

 fluid, contractile substance, to which he gave the name of Sarcode. A 

 similar substance occurring in the cells of plants was afterwards studied 

 by Hugo von Mohl, and named by him Protoplasm. It remained for 

 Max Schultze to demonstrate that the sarcode of animals and the proto- 

 plasm of plants were identical. 



The conclusions of Max Schultze have been in all respects confirmed 

 by subsequent research, and it has further been rendered certain that this 

 same protoplasm lies at the base of all the phenomena of life, whether in 

 the animal or the vegetable kingdom. Thus has arisen the most important 

 and significant generalisation in the whole domain of biological science. 



Within the last few years protoplasm has again been made a subject 

 of special study, unexpected and often startling facts have been brought 

 to light, and a voluminous literature has gathered round this new centre 

 of research. I believe, therefore, that I cannot do better than call your 

 attention to some of the more important results of these inquiries, and 

 endeavour to give you some knowledge of the properties of protoplasm, 

 and of the part it plays in the two great kingdoms of organic nature. 



As has just been said, protoplasm lies at the base of every vital pheno- 

 menon. It is, as Huxley has well expressed it, ' the physical basis of life.' 

 Wherever there is life, from its lowest to its highest manifestations, there 

 is protoplasm ; wherever there is protoplasm, there too is life. Thus co- 

 extensive with the whole of organic nature — every vital act being referable 

 to some mode or property of protoplasm — it becomes to the biologist what 

 the ether is to the physicist ; only that instead of being a hypothetical 

 conception, accepted as a reality from its adequacy in the explanation of 

 phenomena, it is a tangible and visible reality, which the chemist may 

 analyse in his laboratory, the biologist scrutinise beneath his microscope 

 and his dissecting needle. 



The chemical composition of protoplasm is very complex, and has not 

 been exactly determined. It may, however, be stated that protoplasm is 

 essentially a combination of albuminoid bodies, and that its principal 

 elements are, therefore, oxygen, carbon, hydrogen, and nitrogen. In its 

 typical state it presents the condition of a semi-fluid substance — a tena- 

 cious, glairy liquid, with a consistence somewhat like that of the white- 

 of an unboiled egg. 1 While we watch it beneath the microscope move- 



1 In speaking of protoplasm as a liquid, it must be borne in mind that this 

 expression refers only to its physical consistence — a condition depending mainly 

 on the amount of water with which it is combined, and subject to considerable 



