752 
Vol. XXIII. No. 9 
Journal of Agricultural Research 
DEVELOPMENT OF THE PYCNIDIUM ON STRAWBERRY 
On strawberry the pycnidial primordium reaches but little size before 
it can be seen in sections that the cells just below the peripheral layer 
at the top are being oriented vertically (PI. 4, F). There are at first 
not more than a half dozen rows, two or three cells in each row, in this 
palisade (PI. 4, G). These appear, as it were, to be thrust against the 
periphery, flattening out the cells so that one would say that the wall 
now consists of only two or three layers of cells, disregarding the buffer 
tissue which is now burrowing through the host above and which takes 
no part in the formation of the wall. The vertically oriented hyphae 
now branch out and their end cells disorganize, the additional pressure 
due to mucilaginous disorganization tending in all cases to play a still 
further part in the organization of the inner-wall cells. These may in turn 
degenerate or, if not, they may divide tangentially or elongate peripher¬ 
ally so that finall y the completed wall consists of five or six layers of 
cells which are two or three times as long as thick. Sclerosis is so long 
delayed that the pycnidium is capable of continued enlargement. 
GROWTH OF THE BUFFER TISSUE AND FORMATION OF THE OSTIOUE 
The formation of the ostiole in perithecia of a few species has been 
described by Fiiisting (z), De Barry (3), Miyabe (4), and others, and it 
has perhaps been assumed that the same principles hold in the develop¬ 
ment of the ostiole of the pycnidium. In some perithecia there is a dis¬ 
organization of a strip of tissue leading from the hymenial cavity to the 
outside. Further enlargement of the ostiole takes place schizogenetically. 
In nature the pycnidia of Schizoparme straminea are deep seated, and 
the papillate ostiole scarcely reaches the surface. The work of rupturing 
the epidermis and other host tissues above is performed by a sort of 
buffer tissue from the outer loose hyphal envelope, the “tissu fendant” 
of Istvanffi (7) or the “Aperturalgewebes ” of Fiiisting (z). An opening 
must be made through the buffer tissue before the spores can be dis¬ 
charged. It will be shown that the ostiolar opening is formed first 
through the wall, then passage way through the buffer tissue will be 
made. The sharp papillate beak results from the upward growth of buds 
from wall cells. 
Soon after the formation of the central cavity has begun, as noted 
above, the cells at the top of the young pycnidial knot multiply rapidly, 
burrow into the epidermis, and increase in size by swelling to form a cone- 
shaped tissue, which is very effective in lifting up, pushing aside, or break¬ 
ing down the host tissues overlying the pycnidium, after which it appears 
above the surface as a whitish or cream-colored hood (PI. 5> F), similar 
to the “ tissu fendant” surmounting the pycnidium of Coniothyrium diplo- 
diella. The perforation of the buffer tissue and the disorganization of 
the wall of the pycnidium in the preliminary stages of ostiole formation 
are two distinct processes, yet they are both closely associated and neces¬ 
sary in the development of the complete apparatus of spore discharge. 
The construction of the ostiole begins at a point in the incipient inner- 
wall tissue above. A few cells next to the central cavity now forming 
(PI. 4, B) begin to disorganize and by swelling provide a small space into 
which adjacent wall cells bud, turning upward (PI. 4, E). In the mean¬ 
time the buffer tissue has developed and performed its function. The 
disorganization of the wall cells progresses so that the ostiolar opening is 
