284 TIMBER AND SOME OF ITS DISEASES [ctUP. 



Decomes collected into a ball (the egg-cell or oospherc) 

 and then a smaller branch with a distinct origin applies 

 itself to the outside of this rounded swelling and 

 pierces its wall by means of a narrow tube : protoplasm 

 from the smaller branch {antheridkmi) is then poured 

 through the tube into the "egg-cell," which thus 

 becomes a fertilized " egg-spore " or oospore. This 

 oospore then acquires a very hard coating, and possesses 

 the remarkable peculiarity that it may be kept in a 

 dormant state for months and even a year or more 

 before it need germinate : for this reason it is often 

 called a resting spore. It has been found that about 

 700,000 oospores may be formed in one cotyledon, and 

 a handful of the infected soil has sufficed to kill 8000 

 seedlings. 



Now, when we know this, and reflect that thousands 

 of these oospores are formed in the rotting seedlings 

 and are washed into the soil of the seed-bed by the 

 rain, it is intelligible why this seed-bed is infected. 

 If seeds are sown there the next spring, the young 

 seedlings are attacked as soon as they come up. 

 These oospores are, in fact, produced in order that the 

 fungus shall not die out as soon as it has exhausted 

 the current year's supply of seedlings ; whereas the 

 conidta^ which soon lose their power of germinating 

 9.re the means by which the parasite rapidly extends 



