( 796 ) 
iaevulan, attack this substance and use it as food as soon as the 
cane sugar fails. We have, however, found that with some precaution 
it is much easier, especially with B. mesentericus , to produce large 
quantities of Iaevulan, than with B. emulsionis; this reposes on the 
circumstance that the former species, particularly at high temperatures, 
about 40°, possesses a very strong vegetative power, whilst the latter 
always grows slowly and has a relatively low temperature optimum, 
below or near 30° C. 
Hence we used for the preparation of Iaevulan the common hay 
bacterium, which is the form of B. mesentericus obtained by accu¬ 
mulation methods, such as the method of potato slices and that of 
malt solutions. But this form is so common in our surroundings and 
so well adapted to the life in cane sugar solutions of for the rest 
different composition, that these, after pasteurisation or short boiling 
and when kept warm, of themselves produce Iaevulan by the devel¬ 
opment of the spontaneous spores of the hay bacillus. Such solutions 
then turn milky and slimy by the formation of the microscopic 
Iaevulan emulsion. 
For the experiments were used large ERLENMEYER-flasks with 500 
cm 3 of a medium of the composition: tapwater, 20% cauesugar, 
0.05% KNO„ and 0.05% K t HP0 4 , cultivated at db 27 3 C. 
This liquid inoculated with B. mesentericus very soon obtains the 
said milky appearance. The same emulsion which to the colonies 
of B. mesentericus and B. emulsionis on cane sugar agarplates gives 
so peculiar a character, is now in large quantity produced in the 
culture liquid, saturated besides with Iaevulan in true solution, which 
causes the strong and characteristic opalisation, not known to us to 
such a degree in any other substance. Besides, at the bottom of the flasks 
a thick transparent slime layer is slowly formed, which also proved to 
consist of Iaevulan, wherein, however, the bacterial bodies themselves 
are accumulated, whilst the liquid above it is poor in bacteria but 
abounds in viscosaccharase and Iaevulan emulsion. The acid formation 
in this solution is slight but not absent. 
The Jaevulan may be precipitated with alcohol for which 50 % 
in the solution is sufficient. Only at a much greater alcohol concentration 
other substances of the liquid also precipitate. By dissolving in boiling 
water and again precipitating the further purification is easy. After 
drying and pulverising a snow white nearly tasteless powder results. 
From a flask as the above which at first contained 100 G. of 
cane sugar, 8 G. of pure dry Iaevulan were obtained after 7 days 
cultivation, there still being in the liquid 20 G. of invert- and 70 G. 
of cane sugar; the slime at the bottom not being collected. 
