6 14 Price.- — Some Studies on the Structure of the Plant Cell 
death point, and so they may have been definitely associated with this 
unhealthy condition. 
In the case of the crystalline particles of the Elodea leaf, there seems 
to be no doubt that they increase in number with decreasing vitality of the 
plant, and experiments were made to observe this. In one series of experi- 
ments, shoots of Elodea were placed in water in the dark, and the leaves 
examined from time to time with dark-ground illumination. 
Nov. 30, 1912. Sap particles few and of typical form. 
Dec. 2. Sap particles increasing in number ; small vesicular inclusions 
also appeared, especially in the edge cells. 
Dec. 3. A large increase in number. The particles quite obvious 
under low powers. 
Dec. 6. A still further increase, nearly all the particles being of 
crystalline form. Under a low power the leaf seemed full of glittering, 
dancing points of light. 
During this observation the leaf cells became poorly nourished, the 
chloroplasts became pale and often retreated to the lateral walls, thus 
rendering observation clearer. There is no doubt that the particles increased 
greatly in number. 
A similar phenomenon seems to occur as the leaves get older — the old 
leaves of a shoot showing many more sap inclusions than the young leaves. 
In Elodea densa under somewhat the same conditions, the crystalline 
particles become comparatively large and ultimately cease movement, 
falling apparently to the bottom of the cell, where they appear as aggrega- 
tions of needle-shaped crystals. 
Particles or corpuscles which apparently correspond in some respects 
with these have been observed in the Fungi by previous investigators, 
notably by Guilliermond (T 3 , and references there cited), and also 
by this method in Saprolegnia and other cases described above. These 
‘ metachromatic corpuscles ’ are frequently present in the vacuoles of the 
hyphae. They are extremely variable in size and animated by Brownian 
movements. They are stated to be here of the nature of reserve material 
(Maire, ’ 03 ), and probably play an important part in the life of these Fungi. 
To quote Guilliermond — ‘ they have been identified in most of the Algae 
and Protozoa, but they do not seem to be represented in the higher plants/ 
This rather seems to identify them from appearance with the sap 
inclusions described, but if they are part of the nutritive apparatus in this 
case, it seems very doubtful whether this identity is more than superficial. 
The method of dark-ground illumination, providing as it does an 
efficient means for the study of these corpuscles, should help to decide their 
nature, and it is hoped to carry out more work in this direction. 
These sap particles provide an interesting case for the study of 
Brownian movement; they are graded in size, and their rate of movement 
