295 



sufficient to nourish the embryo, no matter whether this arises from a fail- 

 ure of the stimulus of fertilization, from the poor position of the various 

 blossoms, from the exhaustion of the tree as a result of a previous heavy 

 crop, or from a proleptic developm.ent of a fruit bud. In consideration of 

 the fact that seed-containing fruits develop better than seedless fruits from 

 the same tree, it is more advisable agriculturally and horticulturally, as long 

 as seedless varieties cannot be cultivated with absolute certainty, to en- 

 courage the possibility of seed formation. 



Even if Ewert has proved that although in orchards of one variety 

 the number of seedless and poorly seeded fruit is large, the fruits producing 

 seeds still predominate, on which account he has asserted that " pure planting" 

 is advisable, yet for the present we would give preference to mixed planting. 

 The practical disadvantages in regard to the protection and harvesting of 

 varieties growing and ripening dififerently may be decreased by cultivating 

 each variety in rows. In avenues of trees at all times that variety which is 

 most nearly ripe should be especially watched. 



The Behavior of Weak Seeds. 



The causes, which have affected the failure, or the poor maturing of 

 the seeds in seedless fruits, have been felt more or less in other cultivated 

 plants, so that we must also consider the behavior of poorly developed seeds. 

 The scanty amount of nutriment must manifest itself in the specific gravity 

 and, in this connection, Clark's^ experiments show that seeds of low specific 

 gravity do not germinate at all while those somewhat heavier germinate 

 sparsely and often produce weak plants. The highest percentage of germi- 

 nation is found in seeds with the highest specific gravity. 



According to Hosaeus'- experiments, normal plants can be produced 

 even from immature, i. e. specifically light, seeds by carefully providing ver}^ 

 favorable conditions. But the death rate is considerably larger in compari- 

 son with that of normal seeds. This refers especially to the use of grain, 

 for example, which had necessarily been harvested in the milk stage. Some- 

 times the immature seeds undergo a sufficient subsequent ripening, outside 

 of their fruit covering, and can then, under certain circumstances, germi- 

 nate more quickly than the incompletely matured ones. According to 

 KinzeP this may occur in parasites of silk varieties (Cuscata) and is very 

 well worth consideration in combatting them. 



At times, with a poor quality of seed, a careful soaking is beneficial in 

 order to shorten as much as possible the time the seed lies in the soil before 

 its germination. Immature seeds especially decay much more quickly, par- 

 ticularly in heavy soils. But this soaking of the seed is disadvantageous 

 because the seed must he longer in the soil ungerminated if a period of 



1 Clark, A., Seed selection according to specific gravity. New York Exper. 

 Stat. Bull. 256. 1904. 



" Deutsche Landwirtsch. Presse, 1875, No. 4. 



3 Kinzel, W., tjber die Keiming' halbreifer und reifer Samen der Gattung Cus- 

 cuta. Landwirtsch. Versuchsstat. 1900. Vol. 54, p. 125. 



