Protoplasm to the action of different liquids. 145 
To obviate the necessity of transferring the specimen from 
the litre-flask to the stage of the microscope, I have recently 
made use of an apparatus by which all handling of the speci- 
men is avoided, and yet by which the object can be placed 
under the action of as large a quantity of liquid as may be 
desirable. 
Reduced to its simplest terms, the apparatus consists of a 
small number of ordinary “chlorid of calcium jars” (i. e. tall 
slender jars provided with an opening near the base), which 
are connected by means of ‘“‘ three way ” tubes, with a common 
tube of small size. The latter tube is inserted into the side of 
a microscopic-cell of simple construction. The best cells for 
the purpose are made of soft rubber, firmly cemented to the 
. slide, and provided with an inflow and an outflow. The object 
to be examined is held without injurious pressure on the under 
side of the thin glass cover, either by delicate floats of glass, or 
better, by threads of glass fastened by wax. As soon as the 
object has been put in place, and the observer is convinced that 
it has suffered no injury by manipulation, the flow of liquid is 
allowed to begin by slightly opening one of the cocks or clamps 
connected with one of the three-way tubes. The object be- 
comes at once bathed in the liquid, and may be subjected to its 
action either under a continuous slow or rapid flow, or to the 
action ef another liquid. which may be substituted by shutting 
off one and turning on another current. In my repetition of 
Pfeffer’s interesting experiments, I was enabled in this manner 
to wash the object with pure water after every exposure, with- 
out removing it from the stage of the microscope. 
It should be further said that the same apparatus also serves 
for the study of differential staining of tissues by various 
coloring matters. 
By a slight modification, it may be applied also to the exam- 
ination of the effect of different liquids with regard to their 
plasmolytic power (de Vries’s experiments in Plasmolysis). 
The application of this apparatus to the cultivation of organ- 
isms under different conditions of nutriment and the like, is 
obvious. Fresh solutions in any amount and number can be 
brought into contact with the submerged parts without even 
momentary exposure of the parts to the air. 
And lastly, by a slight modification of the apparatus, it 1s 
possible to examine without disturbance of the growing plants 
the character of the acid given off by the extremities of roots 
during growth. 
By “due attention to temperature and to the height of the 
column of liquid in the jars, all the necessary physical condi-. 
oe for studies of this character can be kept well under con- 
tro 
