( 429 ) 
Wakker *) already pointed out that in these the young rhizomes 
and rootlets always arise above the basal wound. 
Investigation has shown that immediately after the lesion the 
formation of these organs is prepared, namely by a division in the 
protoplasm. This I could only observe in leaves which were in very 
good condition of life; in these, however, the changes were well 
visible with the naked eve or else with the hand-magnifier. 
Above the basal wound a clear white spot is gradually seen to 
arise, often several millimetres in size. In these places only the 
rootlets are later formed, while in the immediate vicinity of them 
the rhizomes appear. 
Where it was mentioned above (pag. 425) that the wounded leaves 
showed an inclination for forming rootlets, the arising of such a 
white spot was meant. 
The first question now was: what causes this white spot? 
In vigorous cut leaves one sees often already one day after the 
cutting whitish streaks occur, of which no trace can be detected in 
the intact plant. As far as they are rendered visible by a strong hand- 
magnifier they begin at some distance from the top as well as from 
the edges of the leaf, but become soon thicker and proceed in a 
feeble curve (which is concave towards the edge) towards the middle 
and there assemble and proceed together to the leafstalk ; here and 
there they are connected among each other. So their mode of proceeding 
is exactly the same as that of the green currents. 
But also in other respects they behave like these latter: if the 
cut leaf bears a prolification, from the stalk of this latter a bundle 
of these currents passes into the leaf; when the currents meet a 
cross-wound they proceed as far as this, move sideways and when 
they have arrived at the corner of the wound, continue their way 
straight to the leaf-stalk. 
These currents, which sometimes appear light greenish because they 
are seen through the peripheral layer of chlorophyl, consist of a 
very fine-granulated and therefore milky white protoplasm, very dif- 
ferent from the much clearer protoplasm of the green currents, in 
which the chlorophyl-grains are moved along. The white currents 
partly originate from the green ones: these latter are namely seen 
to become feebler when the latter arise, while at the disappearance 
of the white currents the green ones gradually become more distinct 
again. 
1) Die Neubildungen an abgeschrittenen Blättern von Caulerpa prolifera: Versl. 
en Meded. der Kon. Akad. van Wetenschappen te Amsterdam, 1886, 3d series, 
part 2, p. 252. 
