FOR THE ADVANCEMENT OF SCIENCE. 137 



were sometimes raised upon an acre of land, afforded 3 tons of malt 

 and 3| tons of molasses. A specimen of the Haltica nemorum, or 

 turnip-fly, was then exhibited by Mr. Rootsey, which he stated was 

 the only insect which attacked the plant. Some discussion took 

 place as to the best means of preventing its ravages. 



Professor Henslow referred to the formation of sugar in plants, 

 and exhibited a crystal which had fallen from near the corolla of 

 the common Rhododendron. Immediately after the saccharine matter 

 had exuded, it formed a crystal. 



Mr. G. W. Hall called attention to a statement of facts connected 

 with the acceleration of the growth of wheat. The average length 

 of time required for the growth of wheat was about ten months ; 

 but observation had led to the conviction that much of this time 

 might be saved ; and the result has shown that five months have 

 sufficed to produce an abundant crop of wheat (a sample of which 

 was exhibited to the section), by adapting the plant to the soil. The 

 lighter silicious soils, when manured, possessed a warm and stimu- 

 lating character, and conduced to a very rapid growth of plants, 

 but they soon became exhausted ; and it must be evident that an ac- 

 celeration of the growth and ripening of the plants committed to a 

 light soil, and a diminution of the time required for perfecting its 

 crops, must not only be congenial to its character, but tend to eco- 

 nomize and prolong its productive powers. These circumstances had 

 been observed and acted on with the most beneficial results in va- 

 rious ways. 



Tuesday. — Dr. Richardson read a secosad portion of his paper 

 on North American Zoology, embracing the Mammalia, his obser- 

 vations on the species having reference generally to the similarity of 

 the North American Zoological division to that of Europe, and the 

 comparatively small connection with that of South America, not- 

 withstanding their geographical approximation. 



Mr. Bowman read a paper on the mode of ascertaining the age of 

 yew trees, by counting the rings and lines of the trunk ; and in- 

 stanced several experiments which he had made. The mean 

 average of the number of lines which a tree increased in a year was 

 two, or forty-four to the inch ; and the result of his experiments 

 went to prove that De Candolle was wrong in his experiments in this 

 respect — that he made the old trees too young, and the young ones 

 too old. 



Dr. Riley exhibited the stomach of the seal caught in the 

 Severn, and stated that, on preparing the skeleton of the animal, he 

 found from thirty to forty pebbles contained in it ; which fact he 

 mentioned, to point out the manner in which it is said seals catch fish. 

 Mr. Hope produced a hermaphrodite Lucanus from North Ame- 

 rica, and a curious discussion ensued on the subject of these 

 vegetable monstrosities. Mr. Yarrell mentioned similar occurrences 

 which he had observed in lobsters, a fish, and a fowl, in which the 

 double sex was obvious. 



Mr. Hope then read an interesting and elegantly written paper 



VOL. V. NO. XVII. S 



