Notes. 
651 
thickenings, but no stretching of these has taken place, and they have combined 
together to form this cap of cell-wall substance. It seems to me, however, that this 
thickening has not been laid down in the normal manner, but rather according to the 
method, appertaining to the first cell-division, that is to say, each successive thick- 
ening has occupied the entire dome-shaped upper portion of the cell-wall (cf. Poulsen, 
Fig. 61. Explanation of the figures (all magnified about 700 times) Oedogonium spec. : a. Three- 
celled young plant with somewhat abnormal basal cell, indicating a tendency to subdivide into two ; a 
small terminal cap with well-marked stratification is present on the apical cell ; b. Base of a many- 
celled plant with typical basal cell, surrounded by a thick mass of attaching-mucilage. The cells con- 
tain starch-grains and oil-globules ; c. Apex of ditto, with well-developed stratified terminal cap ; d. 
Portion of a filament, showing slight cap-formation on one of the intercalary cells ; e. Basal cell with 
attaching-mucilage ; /. Apex of many-celled filament, which has lost the terminal cap, and become 
somewhat pointed; g. Cluster of young plants, all with typical basal cells and devoid of mucilage; 
some of the basal cells contain oil-globules. 
loc. cit.). It is difficult to conceive how the normal annular thickening should have 
given rise to this solid cap. In an earlier paper 1 I have described an abnormal case 
1 Cf. Fritsch, Structure and Development of young plants in Oedogonium. Ann. ofBot., vol. 
xvi, 1902, p. 480. 
