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germinated in the two succeeding spring seasons, after wintering. By 

 experiments which have been made with fruit kernels and kernels of the 

 Weymouth pine,* or Pinus cembra, we know that fairly prolonged storage 

 (from one month to several months) at a moist, low temperature, either 

 facilitates the germination of seed normally germinating with difficulty, 

 or is the only factor rendering germination possible. 



Even Hojesky's experimentsf. only extended over one germination 

 period, although he lays stress on the necessity for extending these experi- 

 ments over a fairly considerable length of time. 



From Hojesky's articles quoted above we learn that hard-husked 

 clover seed in the soil is subject to most varied influences which mitigate 

 the hard husk. Hojesky has more particularly established that the hard 

 husk of lucerne seed in dry soil during the warm summer months decreases 

 to a very considerable extent. In a small wooden box fiUed with earth, 

 the dry earth reached a temperature of between 40° and 60° Celsitis on five 

 consecutive days dming the month of June, between 11 a.m. and 1 p.m. 

 In as short a period as two days, samples of hard-husked lucerne removed 

 from this earth and planted out germinated to the extent of Si per cent., 

 and to the extent of 100 per cent, if not removed for five days. Duiirig 

 this period the hard husk in kidney vetch decreased by 50 per cent., whilst 

 red clover showed 15 per cent, of germination after five days. The other 

 varieties showed hardly any traces of germination. 



We therefore see that it is only in the case of lucerne that hard husk 

 is entirely eliminated by warming in the soil, kidney vetch improving by 

 50 per cent. This does not mean to say that, by means of some other 

 determining factor, hard husk would not be ehmitiated in those varieties 

 of seed uninfluenced or only slightly affected by mere warming in the soil. 

 Such a factor could be, for instance, keeping the seed at a moist, low tem- 

 perature in the soil during the winter season. This problem remains 

 unsolved, and the nature of hard husk in lucerne seied and the factors 

 influencing it must first be determined. 



Before proceeding to judge hard husk of other clover varieties, we 

 must know what factors tend to ehminate hard husk in each variety and 

 to what extent they do so. Only then will it be possible to assume that the 

 vexed question can be definitely answered. The'question of time is also 

 extremely important in the matter of hard-husked clover seed. 



A mere indication of the presence of hard-husked seed after conclusion 

 of the germination test, with no inclusion of a fixed proportion in the figure 

 for germinative power, is quite an insufficient method of procedure. Even 

 in the case of vegetable seed and seed for trade purposes the quantity of 

 sound seed remaining after conclusion of the germination test is indicated. 

 There is, however, a great difference between clover seed remaining sound 

 in a field laid down for many years, and simUar seed of a plant whose 

 seeds, germinating later, may only come to maturity after the clover 

 crop generally has been taken from the field. Furthermore, it should not 

 be forgotten that in some years a very high percentage of hard husk 

 regularly makes its appearance, especially in lucerne seed, attaining 

 from 40 per cent, to 50 per cent. In such cases it would be quite absurd 

 to compare this seed — of which only from 40 per cent, to 50 per cent, 

 could germinate within the prescribed, period owing to the existence of 

 a large proportion of hard husk — with seed which is several years old and 

 only germinates to the extent of from 40 per cent, to 50 per cent, on 

 account of its age. 



* A. Grisch and G. Lakon ; " Experiments regarding Germination of Kernels 

 of the Weymouth pine." Swiss Agricultural Year-Book, 1923. 



" How Seeds adapt Themselves to Climatic Conditions (even as far as entire 

 Reversion of Germination Period)." By W. Kinzel; No. I. of 1924 of the 

 practical text-books published by the Bavarian Agricultural Institute for the 

 Cultivation and Protection of Plants. 



■f " Hard Husk Clover Seeds." By J. Hojesky. Journal of Austrian 

 Experimental Stations : Nos. 7-12 of 1921. 



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