155 



Thursday, April 10, 1851. Professor Balfour, President, in the 

 chair. 



The following donations to the library were announced: — Transac- 

 tions and Reports of the General Society of Natural History of Swit- 

 zerland, and of the Society of Natural History at Bonn. 



Dr. Balfour stated that Messrs. Lawson & Son had presented 

 fifty-six specimens of woods to the museum at the Botanic Garden. 



Mr. M'Nab exhibited a stem of Statice arborea, from Professor 

 Syme's garden at Millbank, nearly an inch and three quarters in dia- 

 meter ; also a specimen of the stem of Caryota urens, which had been 

 cut down last year in the Botanic Garden. 



Mr. M'Nab exhibited, from the garden of Dr. Neill, a large spe- 

 cimen of Gentiana verna, in full flower, in a pot. The patch was 

 eight inches in diameter, and the number of flowers was 106 ; when 

 first brought into the room all the flowers were closed, but under the 

 influence of gas-light they opened, and in the course of an hour they 

 were fully expanded. Mr. James Thomson (Dr. Neill's gardener) 

 was requested to make a few experiments on the efiects of light and 

 heat upon the plant. The following particulars have since been fur- 

 nished by him : — 



1. On the 11th of April the gentian was placed in a warm plant- 

 stove, the temperature of which was about sixty-three degrees, and 

 the flowers soon opened (in the absence of light), and continued open 

 so long as exposed to the high temperature. 



2. On the 12th of April the plant was removed to a cool room 

 (temperature forty-eight degrees), in which a jet of gas was burning. 

 In this situation the flowers likewise opened about an hour after the 

 plant was put in. 



3. On the 14th of April, about mid-day, the plant, in full bloom, 

 was taken to a cool dark cellar, where the flowers closed almost 

 immediately. 



4. On the 15th of April it was placed in a cold dark place, from six 

 a.m. till two p.m., during which period the flowers were all partially 

 closed ; the plant being then exposed to light, the flowers expanded 

 in about half an hour. 



Mr. M'Nab exhibited a flowering specimen of Lathraea squamaria, 

 from Dr. Neill's garden at Canonmills, where it has been blooming 

 since the beginning of March. This curious root-parasite was re- 

 ceived by Dr. Neill during August, 1846, from the Portugal laurel 

 shrubberies at Melville Castle, where it was introduced many years 

 previously, from the plantations at Arniston. The plants sent to 



