July, 1922] BONNS A STUDY OF CLAVICEPS PURPUREA 
347 
The tendency of the fungus to grow upon the surface of the medium 
rather than to penetrate the mass to any marked degree — a fact noted 
by Meyer — was observed in the first series of corn-meal and rye-seed 
mashes studied. Most probably failure to penetrate is closely related to 
time and desiccation factors, since the fungus, after the initial stages, 
grows comparatively slowly. That this appears to be true is indicated 
m the 500-cc. flask of w^hite corn meal above mentioned, from which the 
mass was removed in toto by breaking the flask, six months after inocula- 
tion (PL XIX, fig. i). The corn-meal mash still contained an abundance 
of moisture, doubtless sufficient for indefinite growth of the fungus. Pro- 
gression of the pellicle along the surfaces bounded by the flask is readily 
noted, and the longitudinal section through the center of the mass shows 
an almost solid layer of fairly compact fungous tissue 2-3 cm. in thickness 
(PI. XIX, fig. 2). This is not an accretion of surface growth, since orig- 
inally the surface of the medium was approximately that of the upper 
surface of the fungus. It is clearly a growth which has penetrated and 
apparently completely utilized the substrate in its metabolism. 
Sections of this growth at two stages show a type of development 
completely at variance with Meyer's descriptions and illustrations of what 
we assume was a similar stage. The older or outer layers do show a denser, 
compacted growth, but not characteristically parallel; neither has the 
basidial development of Meyer's description been confirmed. Contrary 
to his findings that the resting hyphae are not pseudo-parenchymatic, this 
is precisely what the material shows. Indeed, there is a striking analogy 
between transverse sections of a sclerotium (PL XIX, fig. 6) and of the 
fungus in culture. There is a marked development of the surface hyphae 
resembhng an epidermal formation (PL XIX, fig. 3), and an unmistakable 
pseudo-parenchymatic formation in the general mass (PL XIX, figs. 4, 5). 
The pseudo-parenchymatic appearance of the sclerotium is doubtless due 
to a mesh of hyphal elements developed under pressure. It differs in 
essential characters from sections through the culture chiefly in the smaller 
size of the cell-like areas and in the compacted cells forming the outer 
tissues of the sclerotium. We believe the conclusion is warranted that the 
fungus in culture develops a stage analogous to that found in the sclerotium 
and that the differences in scale of the cell-like structure are probably 
due to the fact that in the flask the fungus grew freely, while in the scle- 
rotium growth is confined and subjected to pressure. 
As previously stated, no attempt has been made to emphasize the 
mycological side of the present study, especially since our observations — • 
with the exceptions noted — accord in the main with those of former workers 
in this field. On the other hand, we have found no reports in the literature 
dealing with the physiological properties of Claviceps cultures. Engelke's 
paper, so far as can be learned, does not appear to have been followed 
by work along the line he proposed. The chief interest in the present 
