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growing on the island. Dr. Hooker identifies this with the Thylica arborea 
of Thouars, a tree which, strangely enough, is found in the remote island 
of Tristan d’Acunha. It is a curious problem for those who study insular 
floras to suggest how the [same plant can have established itself on these 
two little specks of land, separated from each other by about five thousand 
miles of ocean. 
The Physiology of Plants . — A good step is being taken in America 
towards the study of physiology of plant life. It seems that in a paper 
entitled “ Observations on the Phenomena of Plant Life,” by Mr. W. S. 
Clark, President of the State Agricultural College of Massachusetts, we 
have (says “ The Academy,” May 15) a record of a most interesting series of 
experiments instituted to determine : 1. The structure, composition, and 
arrangement of the winter buds of hardy trees and shrubs ; 2. The per- 
centage of water to be found in the branches and roots of trees during 
their annual period of repose, as well as when in active growth ; 3. The 
phenomena and cause of the flow of the sap from wounds in trees when 
denuded of their foliage, as well as the flow from the stumps of woody and 
herbaceous plants when cut near the ground in summer ; 4. The structure 
and functions of the bark of exogenous trees, with special reference to the 
circulation of the sap, the formation of wood, and the effects of girdling ; 5. 
The expansive force of growing vegetable tissue. A number of the officers 
and students of the college co-operated with Mr. Clark in conducting the 
investigations, and all the details of the work appear to have been ob- 
served and recorded in a most conscientious manner. The results, generally, 
bear out the theories held by the most eminent physiologists ; but the mar- 
vellous vital forces revealed are surprising, even after all we previously 
knew of the lifting powers of plants. Possibly some of our readers may 
have their doubts respecting the accuracy of the data, and the means em- 
ployed to register the forces. The experiments undertaken to measure the 
expansive force of growing vegetable tissue illustrated this phenomenon in 
a most remarkable and indisputable manner. The subject chosen for this 
purpose was the squash or mammoth pumpkin, Cucurbita maxima. The 
experiments made on it are fully described in “ The Academy ” referred to. 
Mr. Berkeley 1 s Observations on Agaricus ascophorus. — The following 
remarks of this distinguished botanist are from the u Gardeners’ Chronicle ” 
(April 17, 1875) “ We have lately received, through Dr. M. C. Cooke, a 
specimen of Agaricus ascoporus (Peck), sent by that gentlemen from New 
York. The species clearly belongs to the subgenus Flammula, and we 
therefore felt greatly interested in examining the gills for the supposed 
asci. We readily discovered the bodies in question, but we could by no 
means satisfy ourselves that they were really asci containing speridia. The 
singular matter is that besides these bodies there are forked ascidia, which 
are far less numerous than the bodies in question. These, according to 
Mr. Broome’s and our own observations, are shortly pedicellate, somewhat 
top-shaped bodies with a reticulate surface, the reticulations increasing in 
number with the process of growth. We do not at all consider them as 
asci, but as analogous to the hispid bodies which occur on the gills of some 
species of Marasmius , and possibly of the same nature with the echinulate 
bodies which are so obvious on the pileus of Marasmius Hudsoni. It is true 
