586 Summary of Agricultural Experiments, [oct., 



nitrogen contained in them is concerned, and the preference for one 

 or another will depend on the price per unit of nitrogen in each. 



Inoculation of Soil (Univ. Coll., Reading, Bull, vii., Results of 

 Expts. at the Coll. Farm, 1909). — Plots of £ acre were sown with 

 beans in 1908 and 1909 (1) uninoculated, (2) inoculated with a pure 

 culture of nodule organisms, (3) inoculated with nitro-bacterine. In 

 1909 the crop was badly attacked by aphis, and the reliability of the 

 results was thus affected. The average yields in the two years were 

 uninoculated, 220 lb. ; inoculated with pure culture, 220 lb. ; inoculated 

 with nitro-bacterine, 237 lb. 



Foreign Experiments. 



Germination of Pollen (Wisconsin Agric. Expt. Stn. } Research Bul- 

 letin No. 4). — An investigation by E. P. Sandsten is reported in this 

 Bulletin into some of the conditions which influence the germination and 

 fertility of pollen. In testing the influence of sunlight on germination, 

 some results of interest to tomato growers were obtained. Bright sun- 

 shine was shown to be favourable to a good setting of fruit, while 

 rainy and cloudy weather is unfavourable. Experiments in greenhouse 

 culture with tomatoes during the winter months showed conclusively 

 that a greater number of fruits to the cluster was set during a period of 

 bright sunshine than during cloudy weather. The development of the 

 anthers was also greatly retarded by cloudy weather. In the case of 

 apples and plums, sunshine appeared to have little or no effect. 



The effect of low temperatures on pollen was tested as bearing on 

 the question whether a light frost is likely to kill the pollen and thus 

 prevent fruit from setting. Temperatures a little below freezing-point 

 were not seriously injurious to the pollen of apple, pear, and plum. 

 In the case of cherry and peach about one-half of the pollen failed to 

 germinate after exposure. The pistils of the apple, pear, peach, plum, 

 and cherry proved more susceptible to the low temperature than pollen, 

 so that a heavy frost will kill the pistil while it may not injure the 

 ripe pollen to any degree. In this connection it is mentioned that it 

 is often thought that the juice of the stigma becomes diluted and 

 washed off during heavy and prolonged rains ; observations appear to 

 show, however, that the stigma is not seriously injured by rain, though 

 prolonged rain prevents the proper dispersion of pollen during the period 

 of receptivity of the stigma, which lasts only for a few days. 



To determine the possible influence of cultivation and manuring 

 upon the production and fertility of pollen, apple pollen was gathered 

 from a neglected orchard, which, according to the owner, had not been 

 sprayed, cultivated, or manured since it was planted nineteen years ago. 

 The trees showed abundant evidence of neglect. Pollen was taken from 

 six different trees and also from six trees in a highly cultivated orchard 

 close by. The differences in the percentage of germination from pollen 

 in the neglected orchard as compared with those of the cultivated 

 orchard were not strikingly great, though great enough to demonstrate 

 the fact that this, in common with other parts of the tree, was suffering 

 from lack of cultivation. There was enough pollen in the neglected 

 orchard to pollinate all the flowers therein, provided the weather was 

 favourable, but, on the other hand, the size of the pollen was plainly 

 inferior. The pollen grains lacked plumpness, regularity, and size as 



