326 
Garden Work 
zoospores in a short time germinate, thus giving rise to 
a hypha, which penetrates a small seedling, producing 
the disease. 
There is also a sexual stage in this disease. An 
oogonium, or female organ, and an antheridium, or male 
organ, are produced. The antheridium comes in contact 
with the oogonium. The walls at the point of contact are 
absorbed, and the contents of the antheridium pass into the 
oogonium, thus effecting fertilization. The result of this 
is that an oospore is formed. This may either germinate 
at once, giving rise to a small hypha, or it may form a little 
sac, the contents of which divide into zoospores; or, again, 
it may cover itself with a thick coat, and remain dormant 
in the soil for a considerable time, afterwards giving rise to 
the zoospores or mycelium. The zoospore stage is only 
produced when there is sufficient moisture in which they 
can swim. Both conidia and oospores may remain dormant 
in the soil if conditions are not favourable for their g-er- 
mination. Dryness is the great drawback to the develop- 
ment of this disease. Therefore if the seed beds are kept 
on the dry side, there is no fear of it making its appear- 
ance. Another condition which is essential is thin sowing. 
If the seedlings are crowded, and if by any chance they get 
overwatered, Pythium is almost sure to make its appear- 
ance, and, having plenty of plants to feed upon, it is almost 
impossible to check its progress. On the other hand, if 
the seedlings are a fair distance apart, there is not so much 
chance of them beinor overwatered. Even should this 
happen, and if the disease appears, by pulling out a few 
seedlings round the infected ones, and placing the seed 
box or pan in a light, airy position, the disease may be 
