118 GENEKAL HISTORY OF THE KfFUSORIA. 



attention, and for a long time was deemed sufficient proof of the animality 

 of the beings exhibiting it. It is the consequence of the play of the ciliary 

 filaments of each of the component cells of the aggregate organism, which 

 project beyond the common envelope : it consists in a revolution on the axis, 

 and a simultaneous onward movement — not, however, in a straight course, 

 but in an iiTcgular one, representing a spiral or series of curves. " The 

 collective idea of such motions," says Cohn (A. N. H. 1852, x. p. 328), "is 

 best represented by the coiu'se described by a top, which rims through the most 

 varied curves, while at the same time constantly revohing on its axis." 



jS'ageh. (as quoted in J. M. S. i. p. 198) remarks of swarm-cells (zoospores), 

 which many Monads imdoubtedly are, that " under the microscope the motion 

 appears very rapid, somewhat of an infusorial character, consisting in a con- 

 tinual progression, in which the hyahne narrower extremity is usually in 

 front, and the cell is continually turning on its long axis. Although the 

 swarming bears a resemblance to the motion of Lifusoria (i. e. of Ciliated 

 Protozoa), it clearly wants the s23ontaneity of the latter. The Infusoria 

 advance, spring back, turn round, retui-n, all spontaneously ; the swarm- 

 spores piu'sue a imiform and, for the most part, pretty straight com^se, de- 

 \iating from it, or turning round only upon meeting an obstacle, impinging 

 upon which they are diverted into another direction." To this account 

 Siebold {Joe. cit. p. 201) adds that the spores do not retreat, as if frightened, 

 like the Infusoria, when they strike against an object, but " remain close to 

 it, and continue their motions according to the number and arrangement of 

 their ciliary apparatus, in a rotatory or \4bratory way for a little time longer, 

 as if they aimed at overcoming the obstacle by force, until at last, probably in 

 consequence of the death of the cilia, they become still.and germination goes on. 

 ... The movements of the swarm- spores in general have only a short diu'ation. 

 After the spores have come to a state of rest, they usually become attached 

 by the hyaline ciliated extremity, and the locomotive faculty is for ever lost." 

 In the aggregated families the process of reproduction is ever going on in 

 some members of the colony, and the movements are kept up much longer. 

 Braim {Bejuv., R. S. p. 212) represents Chlamydococcus as enjoying a longer 

 duration of motion than is iLsual with the swarming gonidia of Algee, whilst 

 Protococcus viridis forms an intermediate link in this respect between it and 

 the Volvodnece. The kind of movement, he adds, is essentially the same in 

 these organisms as in all active gonidia, namely an uninternipted revolution 

 round the long axis, combined with an advance towards the side of the 

 ciliated point. It is, indeed, in the swarming movement of gonidia and 

 spermatozoida that the phenomena of motion are most striking, "that is, in 

 cells which are either yet without their cclbilose coating, or which never 

 acquii'e one." 



Cohn {B. S. p. 558) states generally that, " leaving out of the question 

 the more highly organized Infusoria furnished with a manifest mouth and 

 a^sophagus, the motion of a large part of the Anentera (Ehr.), the Astoma (Sie- 

 bold), is not essentially different from that of the zoospores of certain Algae." 

 Likewise, in his description of Gonium (Entiu. p. 180), he observes that the 

 movements of this organism resemble in every particular those of Stephano- 

 sjjlicera, Chlamydococcus, and other swarming- cells, " which certainly do not 

 bear at all the character of pui^posing, conscious volition, but appear as an 

 acti\T.ty determined not by any external causes, but by internal causes in the 

 organization and vital processes." {A. N. H. 1852, x. p. 328.) 



The character of the locomotion of Phytozoa may be described in brief as 

 ' automatic ;' accepting that term as physiologists now agree to do, to distin- 

 guish such motion from the voluntary movements of animals. It cannot be 



