CHAP.III.] of Cell-membrane in Plants. 291 



apertures in which he considers as of secondary importance. It 

 is still more striking that Meyen expressly rejects on page 120 

 the fact established two years before by von Mohl that the pits 

 of parenchyma are thinner spots, and treats the various pit- 

 formations of the cell-wall as raised portions of the surface. 



In the first volume of his later work the ' Neues System,' 

 Meyen gives a detailed account of phytotomy, which accords 

 on the whole with the scheme developed in the book we have 

 been examining, and as might be expected he corrects many 

 errors, adduces many new observations, and introduces us to 

 many steps in advance of former knowledge ; we shall recur 

 to some of his later views in ensuing portions of this history 

 with which they are more in connection, remarking only here, 

 that Meyen paid more attention to the contents of the cell 

 than his contemporaries, and especially made a number of 

 observations on the streaming movement, without however 

 recognising the peculiar nature of the protoplasm which is its 

 substratum. The cell-wall, which he had once considered to 

 be homogeneous, he afterwards believed to be composed of 

 fine fibres, a view resting on correct but insufficient observation 

 and afterwards set right by von Mohl and Nageli. 



It is scarcely possible to imagine a more striking contrast 

 between two men pursuing the same science than that between 

 Meyen and his much more important contemporary Hugo von 

 Mohl ; Meyen was more a writer than an investigator ; von Mohl 

 wrote comparatively little in a long time, and only after most 

 careful investigation ; Meyen attended more to the habit, the 

 collective impression produced by objects seen with the micro- 

 scope, von Mohl troubled himself little about this, and always 

 went back to the foundation and true inner connection of the 

 structural relations ; Meyen quickly formed his judgment, von 

 Mohl often delayed his even after long investigation ; Meyen 

 was not critical, though always prone to opposition, in von Mohl 

 the critical power much overweighed that of constructive 

 thought. Meyen has not so much contributed to the definitive 



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