28 SWIMMING AND CREEPING PROTOPLASTS. 
in a plant, so that, as in every other community, some of the members undertake 
one function, some another. The older cells in these plants often lose their living 
protoplasts, and then, for the most part, serve as an uninhabited foundation to the 
entire edifice, which may thus be penetrated by air and water channels. The proto- 
plasts have meanwhile erected new stories for themselves and their posterity on 
the old deserted foundations, and are pursuing their indefatigable labours in the little 
chambers of these upper stories. This work of the living protoplasts consists in 
absorbing nutriment, increasing their own substance, maturing offspring, searching 
for the places which offer most favourable conditions with a view to an eventual 
transmigration and to colonization by their families; and lastly, securing the region 
where all these tasks are performed against injurious external influences. The 
sequence of these labours is always governed by conditions of time and place. 
Many of them are only to be observed with difficulty in their actual performance 
and are first recognized in their perfected products, while others are attended by 
very striking phenomena and are easily followed in their progress. 
2. MOVEMENTS OF PROTOPLASTS. 
Swimming and creeping protoplasts. —Movements of protoplasm in cell-cavities —Movements 
of Volvocinez, Diatomaces, Oscillarize, and Bacteria. 
SWIMMING AND CREEPING PROTOPLASTS. 
Among the most striking phenomena observed in connection with living proto- 
plasts are, without question, the temporary locomotion of the protoplast as a whole 
and the displacement and investment of its several particles. The freest motion is 
of course exhibited by protoplasts which are not inclosed in cell-cavities, but have 
forsaken their dwelling and are wandering about in liquid media. Their number, 
as well as the variety of their forms, is extremely great. These naked protoplasts 
are evolved by several thousands of kinds of cryptogamic plants, at the moment of 
sexual or asexual reproduction in these plants. The escape from the enveloping 
cell-wall alone takes place in countless different ways, though the process, as a whole, 
is conducted in the manner already described in the case of Vaucheria clavata. 
Sometimes a single comparatively large protoplast glides out of the opened cell by 
itself; at other times, before the cell opens the protoplasmic body divides into several 
parts—often into a great number—and then a whole swarm of protoplasts struggle 
out. 
These swarming protoplasts differ considerably in form. Usually their outline 
is almost ellipsoidal or oval; but pear-shaped, top-shaped, and spindle-shaped forms 
also occur. Often the body of the protoplast is spirally twisted like a corkscrew, 
and has in addition one end spatulate or clavate. Thread-like processes, definite in 
number and dimensions and arranged variously, according to the kind of protoplast, 
