Habits of Anthophysa Miilleri. 431 



Under a low magnifying-power this floccose matter appears 

 to consist of clusters of very jagged, irregularly branching and 

 contorted, semitransparent, intertwined stems, and projecting 

 tapex'ing and flexible twigs. Each of the tips of the latter sus- 

 tains a single more or less globose mass of spindle-shaped 

 bodies, which radiate from a common centre of attachment, and 

 are kept in a constant agitation by the spasmodic jerks of a 

 long, stout, usually rigid, arcuate filament, with which the free 

 end of each one is endowed. The whole bristling mass revolves 

 alternately from right to left and from left to right, whirling 

 upon its slender pivot with such a degree of freedom that one 

 might almost suspect that it merely rested upon it and had no 

 truer adhesion to it than the juggler's top to the end of the 

 baton upon which it spins. The largest of these twirling groups 

 contains as many as fifty fusiform bodies ; but most frequently 

 not more than half that number are grouped together, and from 

 this they vary in decreasing quantities down to only one or two 

 upon each filamentous twig. In the last instances the bodies 

 are comparatively quiet, scarcely moving out of focus at each 

 spasmodic twitch of the arcuate filament. On this account, and 

 because they offer an unobstructed view, the latter are by far 

 the most available as objects for the investigation of their internal 

 organization. 



The relationship of the individual monads to the whole colony 

 must, however, be studied where they are more numerously con- 

 gregated, since, as will be shown presently, each monad sus- 

 tains a definite relation to every other one, and to the twig to 

 which it is attached. The lai'ger colonies are frequently to be 

 found swimming freely, with a rolling motion similar to that 

 with which Volvox progresses. As a natural concomitant to this 

 fact, twigs are to be met with here and there which do not bear 

 anything at their tips. The colonies seem to break away very 

 easily ; and on this account the specimens should not be lifted 

 out of the water when transferring them to the watch-glass or 

 whatever sort of observing-trough is used. 



Form, 6fc. — The adult monads have a truncate fusiform shape, 

 and arc slightly but quite appreciably flattened on two opposite 

 sides, so that in an end view they appear to be broadly oval 

 transversely. The attached end tapers gradually to a point; 

 and on this account it is difficult to determine where the body 

 ends and the twig begins. All of the members of a group radiate 

 from a common point of attachment, to which they adhere by 

 their tapering filamentous ends. The free end is truncate; but 

 one corner of it, as if in continuation of the line along which 

 the opposite flattened sides meet, projects in the form of a 

 rather blunt triangular beak. At the inner edge of the base of 



30* 



