254 The Botanical Gazette. [June, 
and the methods of micro-technique. For advanced students 
the laboratory is daily open, and there, under the direction of 
the teacher and his assistants, they attempt independently the 
solution of special problems. 
Schleiden’s ‘‘Grundziige der wissenschaftliche Botanik” 
drove all other text- and hand-books from the field, and held 
for along time its supremacy. The material to be worked 
over increased so remarkably during the forties and fifties, 
and so many new problems presented themselves, that it 
seemed indeed no easy task to bring everything together into 
a text-book. Schacht’s ‘‘Lehrbuch der Anatomie und Physi- 
ologie,” published in 1856, and Wilkomm’s ‘‘Anleitung zum 
Studium der wissenschaftlichen Botanik,” could not lay claim to 
having filled the gaps. This was first accomplished in 1868 by 
Sachs’s ‘‘Lehrbuch der Botanik,” which soon, in foreign lands as 
in Germany, gainedthe supremacy. The editions of this book 
followed in rapid succession, until Sachs refused to work the 
the book over again. . A summary of Sachs’s text-book by 
Prantl, which in its successive editions adapted itself to the 
developments of the science, may be regarded as the text- 
book which is now most widely distributed among those who 
are learning the science. The number of such text-books has 
increased remarkably of late, and an exhaustive revision of 
Sachs’s book has been recently undertaken by Frank.’? - 
The charts which now beautify the walls of almost every 
botanical lecture-room are indisputably important aids in 
teaching botany. Of these, certainly those by Kny are mod- 
els. They were drawn either by himself, or under his direction, 
especially for teaching purposes, and were often preceded by 
special studies of the objects represented. The results of 
these investigations are presented in special pamphlets that 
serve at the same time as descriptions of the plates which 
they accompany. The wall-charts by Dodel-Port, and also 
those by Frank and Tschirch, are commendable and widely 
used. In most lecture-rooms microscopic preparations are 
when the microscopic figures are projected by means of a solar 
microscope. In other places, the electric light is used for the 
same purpose, or the photogrammes by L. Koc (of Heidel- 
berg), are thrown upon the screen by the sciopticon. 
11This has now appeared in two volumes.—G. 2: 
