TEMPORARY MOUNTS AND MICROCHEMICAL TESTS 77 
razor and judicious teasing with a pair of needles will give a fair insight 
into the anatomy of the higher plants without demanding any further 
knowledge of technic. This rough work is a very desirable ante¬ 
cedent to the study of microtome sections, because most students see 
in a series of microtome sections only a series of sections when, in the 
mind’s eye, they ought to see the object building itself up in length, 
breadth, and thickness as they pass from one section to another. 
The movements of protoplasm can, of course, be studied only in 
the living material. Every laboratory should keep Chara growing 
at every season of the year. Mount a small portion and note the 
movements in the internodal cells. Avoid any pressure and any 
lowering of the temperature. A gentle raising of the temperature 
will accelerate the movements. A leaf of Elodea shows the move¬ 
ments very clearly, especially in the midrib region. The stamen hairs 
of Tradescantia have long been used, their color, resembling a faint 
haematoxylin stain, making them particularly favorable. Stinging 
hairs show a brisk movement if they are mounted quickly and without 
injury. Fortunately, the common onion always furnishes favorable 
material for demonstrating the movements of protoplasm. Strip 
the epidermis from one of the inner scales of the bulb and mount 
in water. The granules may appear to better advantage in yellow 
light, like that of an ordinary kerosene lamp. 
The discharge of spores and gametes should be observed in the 
living material: the difference in the behavior of spores and gametes 
is very striking and can be appreciated only while they are alive. 
Most aspects of growth and movement can be studied best in the 
living condition. In short, it is well to make a preliminary study of 
everything. The germination of spores and the growth of pollen 
tubes can be studied in _ 
the hanging drop. For , LI.. 1 1 . .. [ 
facilitating such cultures ^ 17 _ The hanging ^ rop culture 
there are many devices, 
such as hollow-ground slides, glass rings, rubber rings, etc. (Fig. 17). 
A device which is better for most purposes, and which is easily made 
by any student, is shown in Figure 18. 
A square or round hole f inch in diameter is cut in a piece of 
pasteboard | inch thick, 1 inch wide, and 1J inches long. The paste¬ 
board is then boiled to sterilize it and to make it fit more closely to 
the slide. While the pasteboard is still wet, press it to the slide, make 
