THE PROPERTIES OF PROTOPLASM. 71 



the past twenty years, through the more exact information obtained 

 in regard to the lowest kinds of organisms. Yet the idea had been 

 grasjjed more tlian half a eentury ago ; for the " primordial slime " 

 which Lorenz Oken proclaimed in 1809 to be the original source 

 of life, and the material basis of all living bodies, possessed in all 

 essentials the same qualities and the same importance now ascribed 

 to protoplasm; and the sarcode so called, which in 1835 was pointed 

 out by the French zoologist Felix Dujardin as the only living sub- 

 stance in the body of rhizopods and other inferior primitive animals, 

 is identical with protoplasm. But when Schleiden and Schwann, in 

 1838, developed their cell theory, they were not acquainted with the 

 fundamental significance of protoplasm. Even Hugo Mohl, who in 

 1846 was the first to apply the name protoplasm to the peculiar serous 

 and mobile substance in the interior of vegetable cells, and who per- 

 ceived its high importance, was very far from understanding its sig- 

 nificance in relation to all organisms. Not until Ferdinand Cohn 

 (1850), and more fully Franz XJnger (1855), had established the iden^ 

 tity of the animate and contractile protoplasm in vegetable cells and 

 the sarcode of the lower animals, could Max Schultze in 1858-61 

 elaborate this protoplasm theory of the sarcode, so as to proclaim 

 protoplasm to be the most essential and important constituent of all 

 organic cells, and to show that the bag or husk of the cell, the cellu- 

 lar membrane, and the intercellular substances, are but secondary 

 parts of the cell, and are frequently wanting. In a similar manner 

 Lionel Beale (1862) distinguished such primary forming and second- 

 ary formed substances in all organic tissues, and gave to protoplasm, 

 including the cellular germ, the name of " germinal matter," and tp 

 all the other substances entering into the composition of tissues, being 

 secondary and produced, the name of " formed matter." 



The protoplasm theory received a wide and thorough illustration 

 from the study of rhizopods which Ernst Haeckel published in 1862 

 in his " Monographic der Radiolarien," and its complete application in 

 the " Gencrelle Morphologic der Organismen" by the same naturalist. 

 Ilaeckel distinguishes in these works, for the first time, between 

 gerraless protoplasm, consisting only of plastids called cytods by him, 

 and the germ-containing real ceils, the elementary organism of which 

 consists already of two difierent essential parts, germ and protoplasm. 

 He conceived the cytods and cells as two different gradations of plas- 

 tids, of organic elementary individuals, or as " individuals of the 

 first order," and adopted entirely, in regard to the individual inde- 

 pendence of the plastids, the ideas which had been set forth by Ru- 

 dolf Yirchow and Ernst Brilcke. 



Virchow, w^hose " Cellular-Pathologie " contains the most complete' 

 application of the cell theory to pathology, called the cells and the 

 *' cell territories " belonging to them the individual hearth or source of 

 life ; Brilcke designated them as " elementary organisms." The plas- 



