

238 botanical gazette. [ October, 



distributed, rather than how they are related to each other 

 in manner of growth and as respects their origin. With the 

 cell contents they had comparatively little to do. They were 

 busy with the constituents of the framework. 



There appears to have been a strong suspicion on the part 

 of some botanists during that period that all this study of the 

 skeleton of the plant failed to go to the bottom of the ques- 

 tion. The only wonder is that with their scanty and un- 

 trustworthy chemical appliances and with their very imper- 

 fect lenses they accomplished so much. May I remind you 

 that the element iodine, which is the most important reagent 

 in the examination of the contents of vegetable cells, was not 

 employed until the year 1812 ; and, further, that no good 

 achromatic and aplanatic lenses, of even moderately high 

 power, were constructed until 1827. 



Noting the more important discoveries of the next period 

 in their order, we come first upon that of the nucleus of veg- 

 etable cells bv Robert Brown in 1833, and one mode of cell 

 division by Mohl in 1835. In 1838', the eccentric Schleiden 

 published his Contributions to Phytogenesis, in which he 

 states substantially that cells of plants can be formed only in 

 a fluid containing, as chief ingredients, sugar and mucus 

 (schleim). By this latter term he designated the nitrogenous 

 matters taken collectively. At his touch all disguises fell, 

 and for the first time the vegetable cell was distinctly recog- 

 nized as a unit of structure always serving as the common 

 basis for the formation of the innumerable shapes of the struc- 

 tural elements. 



Next comes the master, Mohl. Armed with the best op- 

 tical appliance procurable, familiar with the use of the chem- 

 ical reagents then at command, and accustomed to accurate 

 research, he reviews his own earlier work and that of his 

 contemporaries, making rapid advance in the knowledge of 

 the contents of the cell. In 1844, in a paper on the circula- 

 tion within vegetable cells, he speaks of the living mass in 

 each active cell, and distinctly recognizes it as that which is 

 the treasury of stored energy and the vehicle of energy 

 under release. He describes it as that which builds shapely 

 forms out of unformed matter and at first hands. This sub- 

 stance he names -proto-plasma^ 



2 "Da wie schon bemerkt diese zahe Fliissigkeit iiberall, wo Zellen entstehen wllen, 

 den ersten, die k'uiftigen Zellen andeutenden festen Bildungen vorausgeht, daw 1 / ter "y 

 annehmen m seo dass dieselbe das Material fur die Bildung des Nucleus una aes rxi 

 mordialsehlauehes liefert, indem diese nicht nurin der naehsten raumlichen VerDinauns 

 mit derselben stehen, sondern aueh auf Jod auf analoge, Weise reagireu, das also mi 

 Organisation der Process ist, vveleher die Entstehung der neuen Zelle einleitet, so nia ^. 

 wohl gerecbtfertigt sein, wenn ich zur Bezeiclmunu dieser Substanz cine auf diese pn> 

 ologlsche Function sich beziehende Benenuung in dem Worte Protoplasma vorscniage. 



