PH ZOPHYCEZ 97 
intercalary transverse divisions. Then follow vertical 
divisions in greater or less number until the axis, 
which terminates upwards in a hair, commonly con- 
sists of tiers of four or more cells. At the base, at 
least while transverse division continues, the axis 
remains composed of a single row of cells. The 
external cells of the upper portion produce short 
processes which bear cell-rows or sporangia. These 
branches terminate in hairs, and frequently bear 
farther branches similarly tipped, which in turn bear 
reproductive organs or more rarely branches again. 
The unilocular’ sporangia are globular or slightly 
ovate, with a small wart at the apex, and occur 
singly or in whorls on the axis and branches, being 
morphologically the equivalent of branches. The 
plurilocular sporangia are cylindrical and usually of 
one row of loculi,and are borne singly and in tufts on 
the short processes of the axis. There are differences 
of size among them, and this difference indicates a 
farther one—viz., in the nature of the contents. 
The small sporangia give rise generally to four 
large gametes, the others six to twelve (commonly 
eight) gametes. Conjugation takes place only 
between a large gamete and a small one, and 
apparently both when they are in a state of mobility 
and also at the moment of coming to rest. The 
point of contact is the hyaline part when they are in 
a semi-mobile state, but when fully mobile there 
is no general rule in this respect. The large one 
appears to absorb the small one, and after one to 
two hours, nothing but the two pigment spots 
remain. to indicate their previous separate existence. 
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