Vi PROCEEDINGS OF THE ROYAL HORTICULTURAL SOCIETY. 



do with the carpellary whorl, though it was true that A. P. de 

 Candolle had considered the rind of the Orange to arise from the 

 development of the disc. An examination of the flower in the 

 course of its development, and indeed, in the mature state, is 

 sufficient to show that this explanation is not correct. The speci- 

 mens on the table were instances of " intra- carpellary prolifica- 

 tion," and the formation of a second whorl of carpels above and 

 within the first. As the'inner carpels had as perfect rind as the 

 outer ones, it was clear that the rind was neither a development 

 of the disc, nor the representative of an outer and abortive row 

 of carpels. 



Cracking of Trees from Frost. — From Mr. C. Noble came a 

 characteristic drawing, showing the effects of frost in splitting 

 the bark and the young wood of the Spanish Chestnut. The 

 fissure was longitudinal and of considerable length, and occurred 

 on the north side of the tree. 



We append an illustration (fig. 45) of trees ruptured by frost, 

 with the following explanation as made by the late Dr. 

 Caspary : — 



No. 1. — Oak with a frost cleft / under a knot a ; w, border of over-growth. 

 No. 2. — Horse Chestnut with a frost clef /which crosses an injury in the 



bark r, whence the decay had penetrated into the wood the depth 



of half an inch. 



No. 3.— Ash. The frost cleft /— /' follows the direction of a cut previously 

 made in the bark, s — s', except in the upper part, where it diverges 

 to the left. In another cut s" there is a second frost cleft f". 



No. 4. — Plan of a Lime tree previously split by frost, but having an over- 

 growth, a c, cavity of old cleft ; h', old wood ; h, young wood ; 

 b, bark ; n, place where it has overgrown. 



No. 5. — Plan of same tree as No. 4, after being re-split in a subsequent 

 winter, b, h, h', as in No. 4 ; / b g c, line of rupture of the bark ; 

 b a, c d, lines of rupture of the young wood ; a e, d c, concave 

 sides of cavity. 



Plant Diseases. — A letter from Professor Sorauer was read 

 suggesting the desirability of co-operation on the part of the 

 Committee with an association lately inaugurated in Germany 

 for the purpose of studying the diseases of plants grown for agri- 

 cultural purposes, and of instituting conjoint action in the matter 

 of prevention or remedy. Professor Sorauer's proposals received 

 the sympathy of the members present. 



