182 VEGETABLE PHYSIOLOGY 
elements enter into very close relationship with protoplasm, 
the former at any rate being in all probability a constituent 
of its molecule. 
Sulphur is only taken up by the higher plants in the form 
of sulphates of some of the metals of the other groups or 
of ammonia. Fungi can also utilise salts of sulphurous and 
hydrosulphurous acids when they are presented in dilute 
solutions. 
Phosphorus is associated with the nucleus rather than 
with the cell-protoplasm. It is contained in the substance 
called nuclein to the extent of about 6 per cent. The 
nuclein is apparently chiefly in the chromatin substance 
of the nucleus. Phosphorus is also a constituent of some 
proteins, and is probably present in the enzymes which 
are concerned in the true digestive processes of the plant. 
It occurs in chlorophyll also, according to Hoppe-Seyler, 
whose analysis of this pigment has already been quoted 
(page 149). In a few plants phos- 
phorus is temporarily stored in the 
seeds. Examples are presented by 
the Brazil nut (Bertholletia) and 
the Castor-oil plant (Ricinus), whose 
seeds contain stores of protein 
Fia. 90.—CELL or Rrornvs A . 
Gkn,) GONRAEING: “Rive material in the form of complex 
Armunown Gnams. grains. In the interior of these 
grains there is a small, usually 
round, substance known as a globoid, consisting chiefly of 
a double phosphate of calcium and magnesium (fig. 90), 
which lies side by side with a crystal-like protein body. 
Lecithin, a complex fatty body containing phosphorus, 
is present in actively growing cells in many plants. 
Phosphorus is absorbed by the plant usually, if not 
entirely, in the form of soluble phosphate, most frequently 
a phosphate of calcium. Besides being important as an 
integral part of the living substance, certain observations 
tend to show that it assists materially in the construction 
of proteins, 
