BOOKS AND CURRENT LITERATURE 331 



cell stage and in the rosette embryos as far as they grow. A reduction 

 in the number of cotyledons in Pinus banksiana due to the fusion of 

 two primordia is interpreted as suggesting the origin of di('ot3dedony 

 from polycotj'ledony. The paper includes a description of the writer's 

 technique for handling pine ovules and is illustrated with five plates 

 and three text figures. — J. G. Brown. 



