112 CALIFORNIA FISH AND GAME. 
a close ratio to the width of the leaves; while, strange to say, the ratio 
between the length of the leaves and the weight, after the tenth or 
twelfth foot falls away. This, of course, can easily be explained by the 
fact that the number of leaves also decreases. 
The weights and sizes of leaves of a section of kelp measuring 
forty-five feet were as follows: 
ist 5-foot length 15 oz., largest leaf 20x4 inches, stipe diameter 8/32, 40 leaves 
4th 5-foot length 32 oz., largest leaf 24x4? inches, stipe diameter 12/32, 28 leaves 
5th 5-foot length 20 oz., largest leaf 25x44 inches, stipe diameter 10/32, 19 leaves 
6th 5-foot length 13 oz., largest leaf 26x4 inches, stipe diameter 9/32, 15 leaves 
7th 5-foot length 8 oz., largest leaf 25x4 inches, stipe diameter 8/32, 10 leaves 
Sth 5-foot length 5 oz., largest leaf 18x3 inches, stipe diameter 8/32, 8 leaves 
9th 5-foot length 3 oz., largest leaf 18x22? inches, stipe diameter 8/32, 5 leaves 
The third to fifth foot shows the most rapid changes in growth. 
Up to this point the plant as a whole develops in the same ratio. The 
most even tenor of the plant’s life as far as growth is concerned is found 
between the fifth foot and that portion which just enters the water 
toward the holdfast; in other words it is in that floating portion on the 
surface of the water, and that portion of the plant just below the tidal 
influence, that the most rapid changes take place in the number of 
leaves and the weight per foot. The length of the leaf remains fairly 
constant until such a part is reached that, owing to the more or less 
transparent condition of the water, the natural growth of the leaf is 
affected. 
The above measurements and weights are given simply as examples 
of growing kelp, and really are not sufficient in number nor collected 
from enough different areas or seasons of the year to arrive at a general 
conclusion. 
ENEMIES OF KELP. 
Now that we are utilizing kelp both as a source of revenue and as a 
raw material for manufacturing a commodity, we are jealous of the 
various forms of life that live upon the seaweed. Some are quite 
harmless in their habits; others more destructive, from our point of view. 
A large trochid which feeds upon the kelp, although consuming 
such a small amount as to be negligible, yet clings to the plants in such 
great numbers at certain seasons of the year that it greatly affects the 
calcium content of the output. Some beds of kelp are more affected 
than others. Another caleareous tube worker, the Spirorbis borealis, 
easily mistaken for a small shell, is found sometimes so thick as to give 
the kelp leaves a bleached appearance, literally covering both sides of 
the fronds and extending over quite large areas, increasing the weight 
forty per cent. The T'rochiscus norrisi mentioned above is very much 
heavier in proportion to the Spirorbis, but their number luckily is not 
as great, a square centimeter of the frond holding sixty to seventy 
Spirorbis. Flustra membranacea, a polyzoan, forming a gauze-like 
inerustation on the leaves and stipe and occupying irregular patches, 
sometimes nearly covering the whole frond, also increases the calcium 
percentage. These and many others, although in a lesser capacity, more 
or less affect the general chemical constituents of the plant. 
So far only one gastropod, an aemza, has been found to be really 
destructive to kelp. It really prefers an Egregia plant to a Macrocystis, 
but it is not above devouring the stipe to such dangerous proportions 
that it breaks off and is cast adrift at the first heavy swell or storm 
that passes. 
