182 
Notes. 
[March, 
fluctuations produced by light in a retina provided with the 
“ visual purple ” are different, both quantitatively and qualita- 
tively, from those where the purple is absent. 
According to H. Hoffmann (“ Naturforscher,” xiv., No. 3) the 
damage done to trees by frost is greater in the valleys than on 
hills, and greater in southern than northern exposures. There is 
not a fixed degree of cold necessarily fatal to trees of a certain 
species, but the injurious effedt depends on the extent of the 
variation when a thaw occurs. A cold of - 17 followed by a 
sudden rise to +3 is not more hurtful than a cold —10 abruptly 
changing to + 10. For every species the amount of this ampli- 
tude is peculiar and fixed. The destruction of vegetation in 
warm aspeCts after a severe frost is noticed by Gilbert White 
(“ Selborne,” Letter LXI.). 
According to J. Reinke (“ Botanische Zeitung,” 1880, No. 48) 
protoplasm contains, as its immediate constituents, plastine, 
viteline, myosine, peptone, peptonoid, pepsine, nucleine (?), leci- 
thine, guanine, sarcine, xantine, ammonium carbonate, para- 
cholesterine, traces of cholesterine, ethalium resin, a yellow 
colouring-matter, glycogen, a non-reduCtive sugar, oleic, stearic, 
palmitic, butyric acid (traces), carbonic acid, glycerides and para- 
cholesterides of the fatty acids, calcium stearate, palmitate, oleate, 
laCtate, oxalate, acetate, formiate, phosphate, carbonate, sulphate, 
a magnesium salt (probably a phosphate), potassium phosphate, 
sodium chloride, iron (in an unknown state), and water ! The 
author obtained his material from the fruits of Ethalium septicum. 
He finds that protoplasm contains scarcely 30 per cent of 
albuminoids, and cautions the reader that this substance can no 
longer be spoken of as a coagulum of white of egg. Chemically 
speaking the protoplasm even of the lowest organisms possesses 
a very complex structure. 
“ Science ” comments somewhat unfavourably on a ledture, 
illustrated with experiments, delivered by Dr. Beard before the 
New York Academy of Sciences, on “ Mesmeric Trance.” 
Among the ledtures to be delivered at the London College of 
Surgeons we notice a course on the “ Structure of the Skeleton 
in the Sauropsidae,” by Prof. Parker ; and a course, by Prof. 
Flower, on the “Anatomy, Physiology, and Zoology of the 
Cetacea.” 
Dr. S. V. Clevenger, in an interesting paper in “ Science,” 
suggests* — basing his views upon the observations of Dr. Drys- 
dale and the Rev. W. H. Dallinger, on the Amoeba* — that the 
sexual appetite is in its origin a transformation of hunger. 
According to the Detroit “ Lancet ” the Boston physicians 
have adopted, as a part of their future code, the following : — A 
physician should not append his name, or permit it to be ap- 
pended, to certificates in laudation of speculative health resorts, 
