48 MASSACHUSETTS HORTICULTURAL SOCIETY. 



except when they had been forced m a high temperature, when 

 there was exhaustion because the foliage was not perfected. He 

 thought that if Mr. Calder could place his lilacs, after a due season 

 of rest, in a higher temperature than that in which they had been 

 forced, he could excite them to growth. Plants after re-potting 

 should be put into a bottom heat, and moderately watered and shaded 

 ■ to cause them to make roots. Plants are not exhausted by flower- 

 ing, but by the high temperature, and it is so with the lily of the 

 valley ; he had planted them out, but found it difficult to get a 

 healthy growth. 



C. M. Atkinson said that in 1850 he succeeded Oldaker, who 

 had been for twenty-five years gardener at Lord Sefton's, where 

 they forced lilacs, cabbage roses, Anna Boleyn and pheasant-eyed 

 pinks, etc. These lilacs had been there ever since Oldaker's time ; 

 some of them were grafted on ash and some on privet. They 

 were forced by plunging in a mixture of fermenting material, and 

 after forcing the old wood was cut back and they were planted 

 out. If plants are cared for after forcing they can be preserved 

 for many years. 



The Chairman remarked that Mr. Hovey had said that the dis- 

 tribution of heat over a longer or shorter time in growing a plant 

 made no difference, and asked whether the lilac flowers on the 

 table indicated natural growth drawn from the soil, or from 

 strength stored up in the plant and unnaturally developed. 



Mr. Atkinson thought it difficult to answer this question de- 

 cisivel}', but four weeks seemed to him a very short time to force 

 lilacs into bloom. The French dig up large plants and force 

 without foliage, and one would think this would injure them, but 

 thej' renew their strength so as to force them again the third year. 



Mr. Hovey read from the " Gardener's Chronicle," for January 

 8, 1876, an account of some experiments by M. Alphonse de Can- 

 dolle, on the amount of heat required for the germination of seeds. 

 " Mustard {Sinapis alba), germinated below 32° on the seventeenth 

 day, and it is probable that this minimum might have been re- 

 duced still lower if it had been possible to keep liquid water around 

 the seeds at 31.1° or 30.2°. Between 32° and 41° and 51°, each 

 degree greatly accelerated the germination of Siyiajns. Thus at 

 35.6° fifteen days elapsed ; at 39.2° nine days. Afterwards the 

 advance was more regular, but the rate of progress decreased 

 gradually with each increment of temperature. Between 54° 



