24 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



It is perhaps better to restrict the comparison of results 

 to each species, and not to compare the results for one 

 species with those for another, since, firstly, different species 

 may respond differently to the same treatment, and secondly, 

 in the case of the two species tabulated, there was a difference 

 of a fortnight in the time of sowing. 



In both cases, however, there seemed to be a tendency for 

 increased germination to follow treatment with calcium chloride, 

 iodine, and cold water, as compared with the control. There 

 was decreased germination with warm water at 50° C, while 

 those seeds treated with boiling water failed to germinate at all. 

 Similar sets in the case of Douglas fir produced much the 

 same results. 



The experiments with European larch and Norway spruce 

 were repeated about three months later, with certain additions 

 and modifications of the treatments. Water at 100° C was used, 

 but for fifteen seconds instead of two minutes. The iodine 

 treatment was modified thus : Instead of the aqueous solution 

 employed in the first experiments, a 20 per cent, solution of 

 iodine in absolute alcohol was used, diluted with water 

 10,000 times. Since the solubility of iodine in water is i in 

 5500 approximately, the diluted alcoholic solution was probably 

 merely a saturated solution of iodine in water. 



In general, however, the results confirmed those of the 

 previous sets sown in May. Soaking in water for twenty-four 

 hours and six hours respectively proved beneficial. The 

 modified iodine treatment gave good results, though, on the 

 whole, no better than the simple watery solution of crystals. 

 In both species boiling water, even for fifteen seconds, and 

 treatment with acetic acid seemed to be harmful. 



Further experiments were made with larch, Norway spruce, 

 and Sitka spruce, and in every case, but notably in the case of 

 larch, the seeds treated with iodine were among the first to 

 germinate. Acetic acid on the whole seemed to be harmful, 

 although less so in the case of Sitka spruce. 



In making general conclusions from these experiments, it 

 must be pointed out that the number of seeds employed in 

 each test is too small to provide statistical results which are 

 strictly comparable. The experiments are only preliminary, 

 yet the results obtained suggest that certain treatments of 

 seeds, such as with cold water, iodine, and calcium chloride, 



