BIOLOGY OF ALEURODISCUS 
453 
with an individuality of its own, and with specific staining affinities, then 
these structures are not mitochondria. Kingsbury (14), in calhng atten- 
tion to the danger of basing morphological generalizations upon special 
technique without first ascertaining upon what the technique depends, 
speaks of the difference between these two views as "the issue . . . between 
a process interpretation of structure as against an elementary particle or 
material interpretation" (p. 47), and makes out a strong case in favor of 
the former. 
In the cells of the radicle of Pisum the writer has obtained with various 
so-called mitochondrial fixatives the characteristic granular and rod-like 
structures commonly described as mitochondria. These can not be said 
to be identical with the similar structures described above. With Regaud's 
fixative the former are well brought out, while the latter are only poorly 
preserved. Flemming's medium solution and the formol-chrom-acetic 
fixative, on the other hand, fix the former structures (in Pisum) only poorly 
but preserve the latter well. The structures in the two kinds of tissue 
have this in common, however, that they are preserved by osmic and chromic 
fixatives and not with solutions too strong in acetic acid. 
In 1902 Maire (17) described fibrils of kinoplasm in the basidia of certain 
species of Basidiomycetes studied by him, which extend from the daughter 
nuclei into the sterigmata and are thought to be concerned with the passage 
of the nuclei into the sterigmata. Fries (9) also makes bare mention of 
such structures in the basidia of Nidularia in the sentence (p. 155): "Bis- 
weilen sind auch diinne Cytoplasmastrange vorhanden, die von den Kernen 
aus in die Sterigmaausbuchtungen hinein verliefen." Levine (15) describes 
and figures these kinoplasmic fibrils in certain species of the Boleti and 
believes he has determined that they are maintained as a continuous line of 
connection between the daughter nuclei of the basidium and the centro- 
somes from the time the former move downward into the basidium and the 
latter upward into the sterigmata and finally into the young spores them- 
selves. Of their function he says (p. 173): "It is, perhaps, not entirely 
proven that these fibrillar strands are actively contractile kinoplasmic 
elements which pull the nuclei into the spores, but the appearances in the 
Boleti certainly suggest such a conclusion." The same author further says 
(P- 159)- ''At this stage I have also found another type of fibrils in the 
cytoplasm. These latter run irregularly but in the main lengthwise of the 
basidium. It may be that they are indications of cytoplasmic streaming." 
It seems likely that these latter fibrils are of the same type as those which 
I have observed in Aleurodiscus. As for kinoplasmic fibrils connecting 
the daughter nuclei of the basidium with the centrosomes in the sterigmata 
and spores, I have never seen them in Aleurodiscus. In the first place I 
can not establish the presence of centrosomes. In preparations fixed with 
the osmium and chromium fixatives it would be hopeless to try to find 
centrosomes among the numerous cytoplasmic granules unless they had 
