452 
HARVEY E. STORK 
This fixative was recommended to the writer by M. I'Abbe Licent who used 
it with success in the botanical laboratory of the Sorbonne for fixing fungous 
tissues. His formula is: 
A and B are mixed only at the time of fixing the material, and a change 
soon takes place in the fluid reducing the acetic acid and producing green 
compounds of chromium. The material may be left in the fluid for a few 
days, which then serves as a chromium mordant. 
In general, it appears that the corpuscles and filaments here described 
are well preserved with osmium fixatives, even though some acetic acid is 
present. With strong acetic acid fixatives they are not preserved. Chro- 
mium compounds give good fixation in the presence of formalin. Once 
fixed, they are stained equally well with safranin or haematoxylin stains, 
though they stand out more clearly with the latter. Delafield's, Heiden- 
hain's, and Weigert's haematoxylin methods were used with equal success. 
In the old cytoplasm that is growing vacuolar, the granules are larger 
than in the younger, actively growing regions. Where the fruit bodies are 
attacked by the parasitic Tremella, the basidia undergo a sort of degenera- 
tion and present very large granules. Two such basidia are shown in the 
photomicrograph (fig. i6), and the basidium shown in figure 26 is drawn 
from parasitized tissue. If sections are cut of such parasitized plants in 
formalin (weak solution) with the freezing microtome and mounted in 
water, the large granules stain the characteristic red with Sudan III, 
showing that they are of a fatty nature and that in the course of degeneration 
of the cell the granules undergo a fatty metamorphosis. 
In presenting this paper, the writer is more interested in reporting as 
accurately as possible the observations concerning the cytoplasmic struc- 
tures in question than in urging any particular interpretation of them. 
There has been much written about mitochondria in the last decade. 
Yet we can hardly say that we know what they are. There is no specific 
technique that brings them out and delimits them from other cell con- 
stituents. Of the numerous functions attributed to them much is con- 
jectured and little known for certain. It is difficult to believe that all the 
structures described by various writers in the cells of animal, fungous, and 
higher plant tissues are in the same category. The term mitochondrium 
therefore requires to be defined. If every granular or filamentous structure 
that appears in living cytoplasm and in cytoplasm fixed by various methods 
is to be called a mitochondrium, then the structures we here describe and 
figure are mitochondria. In that sense, it would be a generic term under 
which would fall various types of cytoplasmic structures. If, however, a 
mitochondrium is defined as a living organ of the cell with a specific function, 
80 parts 
5 parts 
15 parts 
B. 
Pure formalin (40 percent) 
