751 
unserviceable. Neither did we deem it suitable to distinguish between 
the two groups of carotinoids by their spectroscopic properties. The 
same holds in Tswerr’s method. He filters solutions of the pigment 
through a column of calcium-carbonate. The carotin will then pass 
through without being adsorbed, while the xanthophyll is left behind. 
Tswett applies this method to separate the different sorts of xantho- 
phyll, that according to him exist. However, since we only look 
for a separation between the two main groups, we have confined 
ourselves to the method of distribution between methylalcohol and 
benzene. 
It was apparent from our results, as Parmer had already shown, 
that cow’s serum contained only carotin *) egg-yolk and fowl’s serum 
only xanthophyll. Human serum yielded results varying with the 
individual from which it was drawn. It usually contained a mixture 
of ecarotin and xanthophyll, carotin mostly preponderating. In only 
one case xanthophyll predominated slightly; in a few cases — very 
rare though — the amounts of xanthophyll and carotin were nearly 
equal. Not unfrequently did we find that along with carotin there 
was only very little xanthophyll. 
In order to determine the solubility in 64 perc. aleohol we have 
extracted carrots, blood-serum and egg-yolk with ether after treat- 
ment with aleobol. 
The ether was pipetted off and evaporated to dryness in fraction- 
ating flasks, in vacuo, at room-temperature (or gentle heating on 
a waterbath). 
Subsequently 64 perc. ethylalcohol was added in each of the 
flasks and shaken up rapidly. The colour of the fluid was taken 
for the index of solubility. 
It then appeared: 
Colour of 64 pere. alcohol. 
Carrots. . . . . +—+4++4+ + 
Beeyvolke ae fend 
Fowl’s serum. . + + + 
Cow’s serum. . . faint 
Human serum . . + + or + + + 
This makes it clear that whereas carotin obtained from carrots 
is easily soluble in 64 perc. ethylaleohol, cow’s serum is almost 
insoluble. 
The pigment from human serum (a mixture of carotin and xan- 
thophyll, carotin most) is sparingly soluble. 
h Parmer rightly observes that also some very small quantities of xanthophyll 
may occur, which will come forth only when working with large quantities of serum. 
