ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
443 
Gelatin Culture Media.* * * § — Dr. Erwin F. Smith gives the following 
hints on the use of gelatin culture media : — The melting point of 
nutrient gelatins increases as more gelatin is added ; it decreases on 
addition of acids and alkalies, and by long boiling. Grape or cane-sugar 
added to nutrient gelatin frequently restrains or entirely prevents lique- 
faction, at the same time stimulating growth. For this reason gelatin 
should be made with beef broth free from sugar. Owing to the fact that 
commercial gelatin contains salts which are neutral or alkaline to litmus, 
but which retard the growth of many organisms, the gelatin medium 
should first be rendered neutral to phenolphthalein, after which, if de- 
sired, it may be acidified to particular acids. A commercial gelatin of 
uniform character, and washed free from all inhibiting acid substances, 
is a desideratum. 
Raffinose as a Food-Material for Aspergillus.t — M. H. Gillot finds 
Raulin’s fluid J the best culture-medium for Aspergillus niger. If raffinose 
is substituted for the saccharose, it is equally consumed by the fungus. 
Aspergillus niger secretes a diastase capable of inverting raffinose, which 
is completely consumed, tbe resulting products being dexLrose and 
gelactose. Oxalic acid is also produced, increasing the acidity of the 
culture-fluid. 
Nutrient Media containing Salivary Gland and Mucin. §— Dr. G. 
Mayer made an elaborate series of experiments to test the effect of the 
presence of salivary gland and mucin in nutritive media on the growth 
of micro-organisms. The results are collated in nine tables in which 
are contrasted the growth of some dozen pathogenic microbes in simple 
bouillon and agar, with the growth on bouillon and agar containing 
salivary gland or mucin. The results are shortly summed up as follows. 
The flesh of young well-nourished animals, especially that of the calf, 
is better suited for microbic growth than that of other and older 
animals. The development on salivary gland is better than that on. 
muscle, and at the same time characteristic growth appearances are 
favoured and promoted. Mucin prepared from bile exerts a somewhat 
inhibitory action on the development of microbes. 
The glands were obtained from different animals, calf, ox, horse, 
pig, sheep, dog. They were first of all very finely minced, then covered 
over wfith an equal bulk of water, and allowed to macerate for 24 hours 
in the cold. The mass was then pressed, and the thick mucoid fluid 
thus obtained was steam sterilised for half an hour. The fluid, which 
is whitish, slightly opalescent, quite neutral, or with only a faintly 
alkaline reaction, was used alone or mixed with 1^ per cent. agar. 
The mucin employed was prepared from bile. It is a yellowish-grey 
powder which becomes sticky on the addition of fluid. It is soluble 
under 70° C. to about 0*7 per cent, in water. This was inspissated by 
evaporating down in a water-bath at C0°-70°, and, after having been 
* Bot. Gazette, xxvii. (1899) p. 128. 
t Acad. R. Belgique, Bull. Sci., 1899, pp. 211-26. 
X Water 1500 ccm. ; tartaric acidf’Ogrm. ; ammonium niirate 4*0; ammonium 
phosphate 0*6; potassium carbonate O' 6; magnesium carbonate O' 25; zinc sul- 
phate 0*07 ; iron sulphate 0 07 ; potassium silicate 0*07 ; sugar-candy 70 grm. 
§ Centralbl. Bakt. u. Par., l te Abt., xxv. (1899) pp. 747-56, 815-26. 
