1895. ] Development of Botany in Germany. 197 
publications, he pursued the further development of the ques- 
tion. While the material studied for the first publication of 
the book was nearly all unstained, in further observations 
stained objects were used, and in the course of these investi- 
gations microscopic technique made not the least important 
of its advances. 
From the moment when the attention of investigators was 
turned to the contents of cells, further researches into the 
nature of the bodies enclosed within the body of the cell 
itself had to be undertaken. Special studies of starch- 
granules, chlorophyll bodies, aleuron-grains, and the like, 
were made by Nigeli, J. Sachs, Th. Hartig, W. Pfeffer, W. 
Schimper, Fr. Schmitz, Arthur Meyer, Zimmermann, and 
others. In this seriesthe discovery of the amylogenic bodies 
by W. SCHIMPER (of Bonn), was of fundamental import- 
ance. 
Nigeli’s mathematical talent, and his desire to fathom the 
causes of these phenomena, led him to deduce from the phe- 
nomena of swelling, double-refraction, growth, and from the 
visible structure of stratifications and striations, a theory as to 
invisible structure of organized bodies. The stratification of 
cell-membranes has since been shown by DIPPEL (Professor 
at the Polytechnic School in Darmstadt), FR. SCHMITZ ® (in 
Greifswald), Strasburger, NOLL (docent in Bonn),and KRABBE 
(docent in Berlin), to be due to growth by apposition. 
Although the theory of growth by intussusception is no longer 
held in the sense in which Nigeli conceived it (for the double 
tefraction of organized bodies has presumably other causes 
than those assigned by Nigeli), yet his micellar theory re- 
Mains as a brilliant conception which must hold a high place 
in the history of our science. Recently Wiesner (of Vienna) 
has put forth other views as to the elementary structure and 
the growth of living-substance, which are quite opposed to 
those of Nigeli. On the other hand,G. BERTHOLD (Gottingen) 
has sought by his studies in the mechanics of protoplasm * to 
explain by physical causes the structure, the formation, and 
the movements of the body of the living cell. Similar in- 
vestigations of the zoological aspects of the question have 
been published by Biitschli and by the physicist Quincke. The 
chemical constituents of the living cell have occupied the at- 
tention of REINKE (Gottingen, now in Kiel), ZACHARIAS (of 
*Died January 28, 1895.—G. J. P. 
“Studien ber Proioplasmamechanik; Leipzig, 1886.—G. J. P. 
