CELL AND PROTOPLASM CONCEPTS 



11 



founder of the cell theory it can be truly 

 said that his contributions to this great 

 theory were inferior to those of many of his 

 predecessors. It is one of the amazing facts 

 of scientific history that in many biological 

 textbooks Schleiden is called the founder 

 of the cell theory, as if he had first discov- 

 ered that all tissues of plants are composed 

 of cells, or that the cell is the universal unit 

 of organic function as well as of structure. 

 His o-\\Ti particular contribution was in his 

 opinion the discovery of the way in which 

 new cells arise, and yet this has been known 

 for a hundred years to be not only funda- 

 mentally wrong but even fantastic. It is 

 still supposed by some biologists that he 

 first set forth the conclusion that the cell 

 leads an independent life. In the be- 

 ginning of his famous Beitrdge he says : 



Each cell leads a double life : an independent one 

 pertaining to its own development alone, and an- 

 other incidental in so far as it has become an 

 integral part of a plant. It is, however, apparent 

 that the vital process of the individual cell must 

 form the very first, absolutely indispensable basis 

 of vegetable physiology and comparative physiol- 

 ogy. (English translation. The Sydenham Society, 

 1847.) 



But thirty years earlier Mirbel had ex- 

 pressed this thought and twelve years be- 

 fore Turpin had stated it with great clar- 

 ity, while eight years earlier it had been set 

 forth by the famous German botanist, 

 Meyen, in a still clearer and more accurate 

 manner. 



It was the method of origin of new cells 

 which Schleiden regarded as his most im- 

 portant contribution. In his Grundziige 

 der wissenschaftlichen Botanik, translated 

 by Ray Lankester and published by the 

 Sydenham Society in 1849, he says (p. 31) : 



Only in a fluid (cytoblastema) containing sugar, 

 dextrine and mucus (protein) can cells be formed. 

 The particles of mucus are drawn together into a 

 cell kernel (cytoblastus) into which penetrates ex- 

 ternal fluid so that the cytoblast is attached on one 

 side and free on the other. 



And again he says (p. 102) : 



Filial cells (blastidia) are formed within mother 

 cells (matrix). . . . The process of the reproduc- 

 tion of cells by the formation of new cells in their 

 interior is a general law in the vegetable kingdom 



and is the foundation of the production of cell- 

 tissue. 



So far as the genesis of new cells is con- 

 cerned, Schleiden 's fantastic views, as ex- 

 pressed, in 1838, in his Beitrdge, that gran- 

 ules (nucleoli) within cells become cyto- 

 blasts (nuclei) and that on one side of 

 these a membrane arises "like a watch 

 crystal on a watch" to form new cells 

 within the old ones — all this could be 

 charitably set down to that liability to 

 error which we all experience if it were not 

 for the fact that he is so lacking in charity 

 toward his predecessors, some of whom hap- 

 pened to be right where he was wrong. For 

 example, he says : 



Sprengel's pretended primitive cells have long 

 since been shown to be solid granules of amylum. 

 To enter upon Easpail's work appears to me in- 

 compatible with the dignity of science. Mirbel 

 does not make any allusion to the process of cell 

 formation. 



After describing von Mohl's account of 

 the origin of new cells by the process of 

 division, Schleiden says : 



After Mohl, Meyen has been the principal advo- 

 cate of this view, believing that he has in numerous 

 instances recognized this process of spontaneous 

 scission and regarding it as almost a general law 

 in plants. In most of the cases adduced by him the 

 fact has simply been invented, not observed. In 

 the instance in which he refers to direct observa- 

 tion on the origin of four pollen cells in the matrix 

 the fact is exactly the reverse. Unger also has 

 again propounded the multiplication of cells by 

 scission as a general law in plants (1840) but with 

 as little truth as Meyen. (Sydenham' Society 

 translation, p. 104.) 



Of much of Meyen 's great work he says, 

 "I still have many doubts, the solution of 

 which I had hoped to have found in his 

 Physiology but hoped in vain." He either 

 underestimated or ignored all the careful 

 work which had been done by previous stu- 

 dents of cells showing that cells arise by 

 division. 



On the whole one gets a very unpleasant 

 picture of Schleiden 's relations to his pre- 

 decessors and contemporaries, and the 

 question forces itself upon us, how did he 

 come to be recognized as the founder of 

 the cell theory? I once heard a distin- 

 guished physiologist say pessimistically 



