CONIFERALES 



287 



The reduction of chromosomes. — The time at which reduction oc- 

 curs varies with the species and the locaUty, and may differ a few 

 days in different years. In the Chicago region, in Pinus laricio, re- 

 duction occurs the first week in May. Dr. Margaeet Ferguson/^^ 



B 



Fig. 290. — A, Pinus laricio, microsporangium on October i; B, the same on Janu- 

 ary 3; C, the same on April 4; D, Taxiis canadensis on October i, showing microspore- 

 mother-cell stage. — After Chamberlain.'" 



whose work on Pinus is the most complete account of the hfe-history 

 of any genus of the conifers, gives about the same date for reduction 

 in Pinus laricio (austriaca), P. rigida, and P. strohus. Her collec- 

 tions were made in the vicinity of Wellesley, Massachusetts. Hof- 

 MEiSTER,^^^ in Germany, found that in Picea and Ahies the pollen 



