20 
of precise chemical analyses of the skeletal parts of living organisms. 
One of the most striking results of Samoilow’s development of this 
new science was greatly helped by the discovery of F. E. Schulze, 
that portions of the skeletal system of the Xenophyophora, a group 
of marine Rhizopods, consisted of almost pure barium sulphate 
in the form of minute granules. According to Samoilow the abund- 
ance of living organisms of this type off the coast of Ceylon amply 
explains the abundance of nodules of barite which can be dredged 
from the sea bottom in the locality, and points to the possibility 
of an abundance of such organisms in the past being the explanation 
of the occurrence of similar nodules of commercial importance 
found in certain marine beds in Europe. On the strength of this 
generalisation he lias been able to trace numerous important occur- 
rences of barite in Russia to a very limited geological horizon, to 
prove their wide extension within, but not above or below this 
horizon, and to predict their extension to regions not hitherto 
recognised as carrying concentrations of barium sulphate. This 
is a fact of far reaching importance in its influence on the work of v 
the economic mineralogist. 
Following on this discovery Samoilow turned his attention to 
one of the chief sources of commercial strontium, viz., the eeJcstite 
(strontium sulphate) deposits of Turkestan. Here again the whole 
of the deposits appeared to be confined to sedimentary rocks of a 
limited horizon and the discovery by (). Hutschli. that strontium 
sulphate was a major component of the skeletal substance of the 
Acaiitharia, a group of Radiolaria, led to the conclusion by Samoilow 
that these eelostite deposits owed their origin to similar causes to 
those which produced the Russian barite deposits, viz., the ex- 
traction from sea water, and concentration of the minute proportion 
of strontium there existing, by the agency of living organisms. 
This conclusion must necessarily affect profoundly all future pros- 
pecting and exploitation of this mineral in sedimentary formations. 
Samoilow has further pointed out the fact that other valuable 
metals, viz., copper, vanadium and manganese are essential and 
concentrated constituents of portions of certain living animal 
organisms and may have been to a much greater extent in past 
ages. He has discussed the extent to which this fact may influence 
our present theories regarding the origin and distribution of those 
necessary metals in the following words : — 
* “ The deficiency of our knowledge with regard to the 
chemical composition of contemporaneous animals is very 
much hindering the progress of the investigation of this 
problem It would scarcely be reasonable 
to suppose that all the facts concerning this problem arc 
restricted to those so recently and so unexpectedly dis- 
* Mini. Mag., 1917, xviii., pp. 97*98. 
