266 GROWTH AND ORIGIN OF MULTICELLULAR PLANTS. 
ordinary interstitial cell-formation. It has been shown by Klebs* 
that whe 
div. he usual 
anner, but as in Cladophora. It is further stated that these 
genes take place only in cane, grape, or milk sugar, or mannite ; 
o light is also necessary. 
In ph sling the above experiments, using cane sugar, I find 
that both the sheath and cell-wall become swollen and sharply 
differentiated from each other, which accounts for both increase in 
on, as also for very irregular form o 
cells developed under such abnormal conditions; the 1 
irective influence of the sheath due to its rigidity being neutralised 
when swollen, and thus ~ ipee flaccid, consequently the in- 
creasing protoplasm extends at r 
The above experiments I consider ‘to prove conclusively that 
the only factor in determining the direction of growth or habit of a 
plant, but rather that the initial idea of direction and multicellular 
pesto or brane the puede bulging outwards and 
forming a new growing-point at those points of the cell where the 
sheath has been rendered pliant by the action of the protoplasm. 
Description or Prats 277, — Fi Gdogonium giganteum Kutz. The 
numbers 1—6 correspond to the ier of pleats forming the ‘“ cap ” of the 
entice eh the _ Pleats Be ‘peeps BC nding to 1—6 respectively, no 
ent. x 500. 
ing oe td. ate, showing the thickening c to be due 
to an ineurving of the call. wall b, which is eae eite from extending by the 
a oe a; 4, pleat du e to rupture of sheath during formation of a previous 
cell. 3. Diagrammatic section of @. — showing the — of cell- 
ar; 6, cell-wall which is pe toc oth at c to form a cell; f, 
sheath secreted 
hyaline mucilagino h the new cell-wall, after rupture o 
the sheath. 4. Isactis plana Thur., te me eke 
a ' to one vegetative and reproductive phase of the 
po re _ di J, ba portion Passe which by ap cr d 
vision produces a new filament. x 300. 5. Ectocarpus tomen 
Lyngb., pete neg rote tion of a vegetative branch, 2, due to extension of a 
* SB. Versamml. i ey u. Aerzte, Sept. 22, 1886. 
% 
