120 
Notes. 
MM. J. Mace and W. Nicati communicate to the “ Comptes 
Rendus ” the results of their researches on colour-blindness. 
In some cases they find the perception of red deficient, that of 
yellow normal, and that of green more acute than in the healthy 
eye. In others the perception of red is abnormally acute ; that 
of yellow, blue, and violet normal, but that of green enfeebled. 
Hence the authors rejedt the theory of Hering, who assumes the 
presence of two distinct photo-chemical substances in the eye, 
the one serving for the perception of red and green, and the 
other of yellow and blue. They consider that there are in the 
retina three photo-chemical substances, corresponding to the 
three fundamental colours of Young and Maxwell— ?.£., red, 
green, and violet. 
M. Lichtenstein reports, to the Academy of Sciences, on the 
Phylloxera. He thinks the insedt-enemies of this invader not 
sufficiently numerous to be of great value. He is engaged with 
experiments on certain insedticide Fungi, such as Empusa musccz, 
but the results as yet are not decisive. 
M. S. Jourdain considers the inner pair of antennae in certain 
Crustacea as undoubtedly organs of sensation, but in default of 
special experimentation he does not feel justified in pronouncing 
them the seat of smell. 
According to M. H. Viallanes (“ Comptes Rendus ”) there 
exists under the hypoderm of insedts a very rich plexus of 
ganglionic cellules, connedted with the nervous centres, and 
giving off sensitive terminal nerve-ramifications. 
Visibility of Minute Objects. — Prof. Abbe recommends mono- 
bromide of naphthaline for mounting diatoms as less inconve- 
nient than the substances used by Mr. J. W. Stephenson (bisul- 
phide carbon, with or without phosphorus, or sulphur in solution). 
The liquid is colourless and oleaginous, with the odour of naph- 
thaline. It is soluble in alcohol and ether, and has a density of 
1 ‘555? with a refradtive index of 1*658, giving therefore, as the 
“ index of visibility,” 22 as against 11 for Canada balsam. It is 
not volatile. The cover glass should be run round with a ring of 
wax; then with a cement of isinglass dissolved in spirit, or 
Canada balsam, rather thick, dissolved in chloroform ; finally 
closing with a solution of shellac. 
The following preservative fluid is given in the “ American 
Journal of Microscopy” (vol. v., pp. 185, 186): — Two parts of 
salicylic acid and one part of borax, dissolved in a sufficient 
quantity of glycerin, and diluted as the nature of the tissue to 
be preserved may require. Preparations so mounted are said to 
be very durable, and there is no danger of the salts crystallising 
out and spoiling the objedt. 
