320 WHAT IS A DESMID? 
less portion which lies just within the membranous cell-wall 
and its lining tissue, called by the German naturalists the pri- 
mordial utricle, and overlying the more solid green mass of 
endochrome and starchy matter; for it has been found that 
these wonderful little plants contain starchy matter very 
much after the manner of their gigantic fellows of the field 
and forest. Members of the genus Closterium have been 
found to afford the best subjects for witnessing this phenom- 
enon, but the use of a good microscope, and a very careful 
arrangement of the focus of the lens, are always necessary to 
display it in a manner at all satisfactory. Some observers 
assert that they have observed this circulation of fluid, not 
only within the iis manm utricle, but between it and the 
cellulose covering ; however this must be a difficult thing to 
see, as these ctas are very closely united in most 
cases. Along the convex edges of the cell, when a magni- 
fying power of about four Kimised diameters is employed, 
it is not very difficult to see indications of this, what may be 
called “sap-motion” first spoken of, especially if the speci- 
men under examination be one in a vigorous state of growth. 
Then there may be seen broad streams of fluid flowing over 
the whole surface of the endochrome, passing from the ends 
towards the centre and back again; and these streams seem 
to detach and carry with dou; from time to time, little oval 
a globular bodies, which, on account of their action upon 
e light, doubtless resulting from their peculiar chemical 
E uno are readily seen, and any of them may be 
singled out and its whole course from one part of the frus- 
tule to another’ traced. Some observers state that these 
minute granules, which seem to be starchy in their compo" - 
3 _ sition, are thus carried on to the chambers or cavities at the 
.. end of the Closterium, and there join the bodies which are — 
. in trembling motion, as has been described ; but my expe- 
jj 2 rience has been that such is not the case, as the number 


the terminal granules does not increase, as would certainly 
be vene d addition took place. On the conti 


