752 
What strikes us most is the different behaviour of the pigment 
of egg-yolk and of fowl’s serum (xanthophyll), the former being 
insoluble, the latter readily soluble. 
These properties are no doubt partly due to the presence of sub- 
stances accompanying the pigments. When purifying the egg-yolk- 
xanthophyll, which is almost insoluble in 64 pere. alcohol, by saponi- 
fying and removing the fats in the ether-solution, the solubility 
increases. Something like it, but in a smaller degree, was witnessed 
in cow’s serum. From this it is evident that some properties of 
lipochromes are markedly influenced by the presence of other sub- 
stances. We have to keep this in mind when studying the lipochromes 
of blood-serum and other human products, since in this case it is 
impossible to examine them in a pure state. This will be easily 
understood when considering that in clinical inquiries the investigator 
has seldom more than a few cubic centimeters at his disposal, while 
Wirrsrärrer and Escurr used 6000 eggs to prepare 2.6 grms. of 
pure yolkpigment and Escuer required 10.000 cow-ovaries to produce 
0.45 grm. of carotin. 
As has been stated above our first investigation showed us that 
in order to prepare lipochrome from bloodserum it is necessary to 
precipitate it with alcohol and after this to extract the precipitate 
with ether. Extraction by shaking the serum with different solvents 
yielded varying and generally bad results. 
KrvKENBERG had also noticed that lipochrome can be extracted 
from cow’s serum only with amylacohol. He insists that other means 
of extraction such as chloroform, ether, methyl-, ethylalcohol are 
not suitable. 
A more extensive inquiry in this direction revealed that no trace 
of pigment could ever be obtained with petroleum ether from cow’s 
serum, human serum or fowl’s serum. 
With ether we most often obtained no pigment from these three 
sera, at other times only little. 
This result does not quite tally with the experience of PArmrr, 
who also gave his attention to this point. He records that from 
cow’s blood the pigment can never be extracted with ether, from 
fowl’s blood always. To what this difference is due, we have not 
been able to make out. Anyhow, it is certain that 8 specimens of 
fowl’s serum, examined by us, did not yield a pigment even after 
being rapidly shaken with pure ether; whereas from two other 
specimens, treated in a similar way, a rather considerable amount 
of pigment could be obtained. 
When shaking cow’s serum with amylalcohol, a trace of pigment 
