The Wohurn Pot-Cidture Experiments, 11)10-11-12. 327 



respectively to •■40 per cent, in {h), •;")(> ])er cent, in (c), '80 per 

 cent, in {d). and I'O per cent, in {e). 



The first oiiservation made was that the presence of magnesia 

 prolonged the incubation period of the seed. Tlie plant, how- 

 ever, seemed to show a darker colour and stronger growth where 

 magnesia was present. As the crop ripened, the straw from the 

 magnesia treatment became distinctly shorter, though of stouter 

 character. The ripening of the crop was, further, retarded by 

 the presence of magnesia. 



The general results as regards the wheat crop of 1907 are 

 well shown in Plate 9, and the harvest results briefly set out 

 were : — 



These results differ somewhat from those of 1906, which 

 showed a regular gain until the ratio of 1 : 1 was exceeded. 

 This may possibly be due to the decision to increase, in 1907, 

 the quantity of lime. Bat, patting together the several years' 

 experiments on this subject, it was found generally that as the 

 ratio of 1 : 1 was approached, there was some increase in the 

 crop, but as soon as the magnesia came into excess, a lowering 

 of the produce took place, and with increasing amounts of 

 magnesia the influence l)ecame a toxic one. 



But this was not the only result obtained, for, on taking out 

 the roots after harvest they were found to have undergone very 

 remarkable alterations, the tj'pe of root formed where magnesia 

 was in excess of lime being quite dift'erent to the ordinary, and 

 being specially marked by its tine and feathery nature and the 

 abundance of root development. These appearances are well 

 brought out in Phite 10, in which are shown the roots of the 



