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 ofier 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 PKOTOPLASTS. 



Swimming and creeping protoplasts. — Movements of protoplasm in cell-cavitiea. — Movements 

 of Volvocinese, Diatomacese, Oscillarije, and Bacteria. 



SWIMMING AND CEEEPING 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 diflferent 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, 



