4 sf: 4 ru i ry : aaah aah ' 
3838 REPORT OF THE COMMISSIONER OF AGRICULTURE. 
i 
aye 
If, after a prolonged rain, a drop of water from a diseased leaf, or | 
from an apparently healthy one growing close by, is examined with 
a good microscope, large numbers of conidia in various stages of ger- 
mination will usually be seen. It is during such periods that the 
healthy leaves are infected; the germ tubes enter the leaf (either by 
directly penetrating the cuticle or through the ‘‘ breathing pores”), 
and once within the tissue they may continue to grow independent 
of external circumstances. 
Conidia sown on healthy leaves of pot-grown strawberry plants, 
which for three days following were kept constantly wet, produced 
the characteristic purple spots in about eighteen days. Similar sow- 
ings on leaves kept constantly dry were not infected, although the 
plants in both cases were cared for alike, except in the matter of 
moisture. 
Repeated sowings of the conidia in solutions employed as fungi- 
cides were made. None germinated in a1 per cent. solution of hy- 
posulphite of soda, or in a one-fourth of 1 per cent. solution of sul- 
phate of copper. A very small quantity of lime in water used in 
these experiments also checked the germination of the conidia, 
Spermogonia.—During the autumn and early winter there is de- 
veloped on the mycelium numerous round or ovoid bodies which, as 
they increase in size, break through the tissues of the leaf, appearing 
on the surface as minute black specks. Some of these bodies are the 
spermogonia, their interior being filled with spermatia. The sper- 
matia have a length of 3, and are about three timesas long as broad. 
They are produced in vast numbers and doubtless serve some impor- 
tant office in the economy of the fungus, but just what that office is 
has never been clearly demonstrated.* 
Perithecia (Wig. d).—By far the larger number of the black bodies 
above mentioned are perithecia. They are the last to come to ma- 
turity, at the time the spermatia are most abundant their interior is 
filled with a clear mass of cells. They are usually somewhat larger 
(90 to 130 in diameter) than the spermogonia, and their outer walls 
are more nearly black and apparently thicker or firmer in texture. 
They are usually partially imbedded in the ruptured leaf-surtace, but 
not infrequently they appear to be resting directly upon it. At the 
top of each there isasmall opening or ostiolum which permits the 
contents to escape at maturity (Fig. e). If the perithecia be exam- 
ined during. the latter part of winter or early spring (they are almost 
always found abundantly on leaves destroyed by blight the previous 
year) the interior will be seen to be filled with numerous transpar- 
ent sacs or asci attached to a thin layer of light-colored tissue resting 
on the botton wall (Fig. e). These sacs are about 504 long and 1041 
diameter above, tapering below to a narrow base. Within them are 
formed the ascospores, usually eight in number in each sac (Wig. 7). 
These are illustrated in Plate I, Fig. g, and are true reproductive 
bodies, designed, no doubt, to preserve the life of the fungus in special 
*A fungus named Septoria aciciulosa, often found associated with Spherella fra- 
garice, has been thought by some to be the spermogonia of the latter, but its spores are 
often two-celled and they germinate without difficulty, contrary to the character of 
spermatia. Possibly it represents the pycnidial stage of the Spheerella, but this is 
very doubtful. Septoria fragarice has also been thought by some to be the sperm- 
ogonial stage of the Sphcerella, but there is no longer any reason for supposing this 
to be the case. Another fungus (Ascochyta fragarie), sometimes found associated. 
with the Spheereila, has been regarded as its pyenidial form, but from our observa- 
tions we can see no reason for accepting this view, although we have occasionally 
found this fungus on leaves destroyed by blight. 
