16 BULLETIN 1191, U. S. DEPARTMENT OF AGRICULTURE. 
SIZE ATTAINED. 
Plants in 50 feet of water at La Jolla have been found with fronds 
floating on the surface a distance of 70 feet. If these plants were 
attached to the bottom, they therefore had a length of 120 feet. The 
majority of plants in the same locality do not apparently reach a 
length of more than 100 feet. In 20 or 25 feet of water plants attain 
a length of 30 or 40 feet, and where 
they have been found growing in 
tidewater on the coast of southern 
California they seldom attain a 
length of more than 10 feet. The 
most vigorous specimens found 
were at San Nicolas. They ap- 
peared to float on the surface for 
about 100 feet and may have had a 
total length of 150 feet. The long- 
est leaves found at San Nicolas 
measured nearly 6 feet, but were 
only 4 inches wide. These were on 
plants of the first or very slender 
type; they were attached to globu- 
lar cysts nearly 14 inches in diam- 
eter. Plants of the typical dM. 
pyrifera associated with them had 
leaves as long as 5 feet, cysts 3 or 4 
EE eat tenes ong, and) mostly about 1 
inch wide, and stipes about’ one- 
third inch thick. The leaves averaged 36 inches long by 3 inches 
wide. Plants of M/. pyrifera have been found there with leaves 50 
by 7 inches, cysts 4 to 6 inches long and sometimes 14 inches wide, 
and stipes one-half inch thick. At Santa Barbara Island leaves of 
the quiet-water form have been found which measured 50 by 10 
inches. These were attached to cysts about 23 inches 
long and 14s inches wide, on stipes one-fourth inch Q--b 
thick. At La Jolla and other mainland beds leaves 
are usually 18 by 30 inches long and 4 to 6 inches wide, [2-"S 
cysts 2 inches by five-eighths inch, and stipes slightly % Es 
more than one-fourth inch thick. Occasional speci- Fic. 9.—Young 
: lant b- 
mens here attain almost the dimensions of San Nicolas  4niy 3 months 
kelps. Holdfasts are from. 1 to 4 feet in diameter, ¢!¢. R= 
averaging less than 2, tidewater plants having hold- stem or stipe 
fasts seldom 1 foot in diameter, with the exception of f[itesize. 
shore Macrocystis. Basal sporophyls are 1 to 2 feet 
long by 1 to 2 inches wide. Large clumps at their best have from 
15 to 20 mature fronds. 
LIFE CYCLE OF AN INDIVIDUAL FROND. 
Properly to understand all the normal and abnormal phenomena of 
destruction and regeneration in Macrocystis, and particularly the 
effects of cutting, it is necessary to consider in detail the life cycle of 
an individual frond. (Figs. 3, 4, 5,9, and 10.) The clustered fruit- 
ing leaves or sporophyls at the base of the plant have been described. 
