8o 
ON THE RESERVE PROTEIN IN PLANTS. 
called proteosomes, with a high refractory power for light.^ 
Upon treatment with iodine solution, they assume a yellow tinge 
and lose their brightness entirely, showing either numerous little 
vacuoles or one large one and being then hollow spheres. To 
distinguish them from starch granules or fat drops is, there¬ 
fore, a very easy matter. Sometimes it suffices to take a little 
piece of fresh bark or a leaf and tear it into little particles 
in a drop of coffein solution and observe the result at once 
under the microscope with a high magnifying power. Thus, 
not only the bright drops mentioned can be seen very soon, 
but also in some early dying cells the change from the bright 
drops to hollow spheres can be observed even without killing 
with iodine. 
With regard to the behavior of the proteosomes, I observed 
the following: the petals of Saxifraga sarmentosa which had 
remained in cold saturated coffein solution and showed then 
numerous proteosomes, were left for 15 hours partly in 1 % HC 1 , 
partly in 1 % HN 0 3 , and partly in dilute phosphotungstic acid. 
The proteosomes were not dissolved but had become turbid. 
Nitric acid had produced a yellowish coloration which became 
stronger on heating. 
The petals of Punica granatum were, after treatment with 
coffein, placed (a) partly in 1 p. mille NH 3 , (b) partly in 1 % 
acetic acid and (c) partly in alcohol of 20 %. After 4 hours it 
was observed that the dilute NH 3 had not produced any vacuoles 
in the proteosomes; it seemed that they had become solid, and 
neither absolute alcohol nor NH 3 of 10% nor acetic acid of 
i % changed them any farther. The portion exposed to the 
dilute acetic acid (b) showed coagulated masses of irregular 
form which were not changed any more by absolute alcohol. 
A portion of proteosomes seemed to have been partly dis¬ 
solved. Those proteosomes (c) which had remained 4 hours 
in alcohol of 20 % were partly transformed to hollow spheres, 
partly to irregular masses which experienced no farther change 
by treatment with absolute alcohol. 
1) Dead cells never give proteosomes on treatment with coffein. If leaves of 
Pæonia albiflora, for instance, are left for 24 hours in 1 °/ 0 acetic acid or for 1 hour 
in vapors of ether, coffein will not produce any more proteosomes while the fresh 
leaves give a very strong reaction. 
