THE NUMERICAL ASPECT OV OAK GALLS. 25 



The other correspoiident writes : " Several workers 

 in the AYest Riding of Yorkshire have noticed that the 

 oak trees which are nnich attacked by Aphilotlriix 

 fecnndafrie usnallj^ produce acorns having pink cotyle- 

 dons. So pink are they that the colour s'hows through 

 the seed covers. Of course this may he only a coinci- 

 dence, but several of us have observed it for some years " 

 (In ht., AY. P. AYinter, Moorhead, Shiplev, December 

 29th, 1907). 



