Grinnellia americana , Harv. 1 1 
formation of three to six transverse walls, lateral branches 
develop, forming the holdfasts of the young plant (Fig. 7 h). 
These are usually only a few cells in length, irregular in outline 
and incurved at the tip, enabling them to fix the young 
plant firmly to its substratum. Because of the nature of its 
holdfasts, the young fronds are often found growing in 
epiphytic fashion on older Grinnellia - plants and other Algae. 
At this period, the rapid growth in the middle of the 
filament is characterized by the appearance of vacuoles and 
the rearrangement of chromatophores in such definitely 
transverse and radiating lines that the appearance of cell- 
division is produced. As the spore continues developing, 
these lines of chromatophores are arranged lengthwise of the 
cells (Fig. 7 c), vacuoles appear and the colour of the contents 
becomes much lighter and almost disappears in the outer 
terminal cells of the filament (Fig. 7 v). 
Cell-division in the germinating spore is limited to one 
plane until the formation of a frond proper begins, when 
fission takes place in two planes along the lines of the collected 
chromatophores ; and subsequently, with the development of 
the midrib, occurs in three planes in the median region of 
the frond. 
For frequent observation of the progress of germination, 
pieces of mica were placed beneath the fronds until sufficiently 
covered with spores. The mica was then transferred to 
shallow dishes of water, and was examined often during the 
early stages of spore development. This recurring disturbance 
proved injurious to the spores, and they seldom survived the 
treatment longer than a week. When unmolested and 
supplied with fresh water daily, they continued to grow for 
a period of two to three weeks. 
To determine the varying effect of different rays of light 
upon their development, dishes containing spores were 
covered with colourless, red and blue glass respectively. These 
receptacles were then protected from direct sunlight, and 
supplied with the boiled sea-water which was changed every 
thirty-six to forty-eight hours. The spores under the colour- 
