276 Phillips on a Comparative Study of the 
ually this growth ceased and the plants remained stationary 
for a season. Then a gradual decline began and no visible 
trace of the organism would be left. In this way the spores 
that had been formed lay dormant until the proper season 
of the following year, and no experimental method seemed 
to cause them to germinate sooner. 
In the study of the organisms, it was the general plan to 
do as much on the living plants as possible. It was often 
found difficult to keep the trichomes in natural surround- 
ings, e. g., in the forms found creeping over the ground 
often the mere mounting in water would bring about 
extreme variation conditions. The organisms were studied 
carefully in their normal conditions under various powers 
of the microscope, the work being performed with Zeiss’ 
achromatic and apochromatic objectives of 2 mm. and 1.5 
mm. focal lengths, and compensating oculars 4, 6, 8 and 18. 
All of the drawings were made with the camera lucida and 
these objectives. Culturing in various nutrient fluids which 
would bring about accentuated or pathological conditions, 
was found to be an extremely useful mode of experimenta- 
tion. Cultures of a full nutrient solution were found to yield 
particularly beautiful results; also fluids which would either 
feed or starve the chromatin were extremely useful. Grow- 
ing in direct and in diffuse sunlight, under different colored 
screens, and in darkness were also tried. Plants were grown 
in weak solutions of different salts, as palladious and plati- 
num chlorides, to assist in bringing out the structure in the 
cell wall, as recommended by Dr. Pennington (62). The 
organisms were also cultivated under natural and artificial 
conditions in a live cell and watched continually for long 
periods of time. In this way the same cell could be observed 
in different stages of its life-history. Intra-vitam staining 
gave very interesting results, especially when carried out on 
the life-slide and continuously watched. By this method 
chromatic and nuclear elements were very nicely contrasted. 
Filaments of Spirogyra were also placed among the trich- 
