384 Royal Society of Edinburgh. 



propulsion of the sap along the vessels, resulting from the opera- 

 tion of endosmose, will explain the descent of the cambium, which, 

 being the nutritious portion of the vegetable fluids, corresponds in 

 its nature to the chyle in animals. 



ROYAL SOCIETY OF EDINBURGH. 



March 27, 1843.—" On the Grovi^th and Migration of the Sea 

 Trout of the Solway (Salmo trutta)." By Mr. John Shaw, Drum- ,v 



lanrig. Communicated by James Wilson, Esq., F.R.S.E. ' 



The author has here pursued the same course of experimental in- 

 quiry regarding the Sea Trout as that formerly followed in relation 

 to the salmon. Having obtained impregnated ova from a pair of 

 spawning fish, he conveyed these ova to his experimental ponds. 

 This was on the 1st of Nov. 183.9, and the young were excluded from 

 the egg in seventy-five days. They resembled salmon of the same 

 age, but were somewhat smaller and paler. They took two years to 

 grow about- 7 inches, and the majority were then converted into 

 smolts, but about one-fourth did not assume the silvery lustre, and 

 this peculiarity, Mr. Shaw thinks, distinguishes a like proportion even 

 in the rivers. He then experimented on the smolts in the natural 

 streams, and found that after descending to the sea they returned as 

 herlings {Sahno albus of Dr. Fleming) in July and August, with an 

 addition to their weight of 7 or 8 ounces. These herlings spawn 

 towards the end of the season of their first ascent, and after revisiting 

 the sea they ascend the rivers again in the ensuing months of May 

 and June, with an average weight of 2~ lbs. This increase takes 

 place almost entirely in the sea. After spawning for the second time, 

 they descend for the third time to the sea, and make their appearance 

 again in fresh water in the course of the ensuing summer, weighing 

 4 lbs. They are now in their fifth year, including the two seasons 

 they had passed as fry, anterior to the assumption of the migratory 

 dress and instinct. Descending seawards for the fourth time, they 

 weigh about 6 lbs. when next seen in the rivers in the course of their 

 sixth summer. These at least were the progressive changes and rates 

 of increase observed by Mr. Shaw in specimens distinctly marked, 

 and carefully noted when retaken successively from year to year. 

 The peculiar marks imposed each season are detailed in his paper, 

 and the whole subject is illustrated by an extensive series of speci- 

 mens from the day of hatching to the middle of the sixth year. These 

 specimens are now in the Society's museum. 



April 17. — Professor Connell read a paper on the Presence of 

 Organic Matter in the purest Water from Terrestrial Sources. 



Sir John MacNeili then read a Biographical Sketch of the late Sir 

 Charles Bell, K.H. 



Dr. Douglass Maclagan read a notice regarding the Bebeeru Tree 

 of British Guiana. Of this last paper we present a brief sketch. 

 The plant bearing the above Indian name, and also called Sipeeri by 

 the Dutch colonists, furnishes the hard and heavy timber known by 

 the name of Greenheart. The object of the present paper was to 



