INTRODUCTION 27 
an incomplete differentiation of reproductive and 
vegetative cells in the plants which possess them. 
It may be so, but the point is by no means 
established. The special amyloplastic function of 
the chromatophore, as distinguished from its 
assimilative one, appears to be limited to that portion 
immediately investing the pyrenoid. Ifthe change of 
size of the pyrenoids be associated with the nutritive 
state of the cell, as appears probable, it would con- 
firm the opinion that they are reserves of proteid. 
In collecting seaweeds between tide-marks the 
nature of the appropriate equipment is so obvious 
as to need little direction. The most convenient 
receptacle for specimens is the ordinary waterproof 
sponge-bag, though a tinned iron milk-can with a 
good lid has its advantages. In no case should glass 
bottles be carried in the hand or pocket, since they 
are a source of danger, and unnecessary. For similar 
reasons a knife is an undesirable companion in 
slippery places, and it is not needed if the collector 
carry a stout stick of the alpenstock pattern, with a 
chisel screwed into one end for scraping off 
specimens, and a small landing-net ring provided 
with a cotton bag instead of a net attached to the 
other end. The stick is useful for support, and the 
bag for securing floating specimens that have been 
detached by the chisel. Wading boots are of great 
advantage, except where there are deep pools, when 
the risk attending immersion is greatly increased by 
their use. 
Though a storm is often more productive than a 
dredging expedition, the specimens are frequently 
