282 TIMBER AND SOME OF ITS DISEASES [chap 



hour and day after day foi seveial weeks, each hypha 

 producing two or more conidia within a few hours of 

 its emergence , hence hundreds of thousands of conidia 

 may be formed in the course of a few days, and if 

 we reflect how Hght the conidia are, and how their 

 zoospores can flit about to considerable distances, it 

 is not surprising that many of them arc shed on to 



Fig 45 — An oogonium, and anthei idium of Pkyto^hihora omniz ora 1 he oogonmm 

 IS the larger rounded body, borne on a brinch of the raycchum it contains an 

 oosphere, in process of being fertili/ed by the protoplasm of the ■^ntheridmm (the 

 smaller body applied to the side of the oogonium) The anthendiura has pierced 

 the u all of the cog mum, by means of a fertiluing tube, through which the contents 

 pass into the oo^^phere, converting the latter into an oospoie (Very highly 

 magnified , after De Bary ) 



the surrounding seedlings, to repeat the story. If wc 

 further bear in mind that not only every puff of wind, 

 but every drop of rain, every beetle, or fly, or mouse, 

 &c , which shakes the diseased seedling may either 

 shake conidia on to the next nearest seedlings or even 

 carry them further, it is clearly intelligible how the 

 infection is brought about, and spreads through the 



