840 ORDER TENTACULIFERA-SUCTORIA. 



however, the investigations of Wrzesniowski,* the mystery up to the present time 

 associated with this very remarkable organism has been satisfactorily dissipated, 

 and Dendrocometes is demonstrated to share all the essential characteristics of the 

 order to which it has been hitherto but provisionally relegated. While in their 

 more ordinary condition the distal terminations of the characteristic antler-like 

 appendages of this type present a simply conical and pointed aspect, Wrzesniowski 

 shows that their terminations are capable of foreshortening and expansion, and that 

 under such conditions they exhibit with a magnifying power of 1200 diameters 

 minute tubular axial canals, forming a channel of communication from the 

 exterior down the main branches into the body of the animalcule. It was further 

 proved by this investigator that these distal terminations of the branchlets possess 

 the faculty of closing upon and holding other Infusoria, the contents of which are 

 then sucked out and transferred to the parenchyma of its own body, after the same 

 manner as an ordinary Acineta incepts the life-juices of its prey through the one or 

 more suctorial tentacles wherewith it holds it captive. Adopting a somewhat fanciful 

 simile, the phenomena attending this seizure and inception of food by Dendrocometes, 

 as represented at PI. XLVIIlA. Figs. 8a and 9, might be appropriately compared 

 to that of a man, his normal alimentary functions being suspended, endowed with 

 the capacity of grasping an orange with his hand, and transferring its juices to his 

 own body through perforations in the tips of his fingers. 



The embryos, as first figured and described by Stein, and more recently investi- 

 gated with great success by Biitschli, f present a hypotrichous aspect, corre- 

 sponding closely with those of Podophrya gemmipara and Ophryodendron abietinum, 

 being ovate with a flattened ventral and convex dorsal surface, the peripheral 

 margin of the former bearing a border of cilia, and having a curved excavated 

 central area of somewhat variable form. These embryos, which are matured singly 

 within the parent, occupy a very considerable portion of its body-cavity, and, without 

 some special provision for their release, their liberation would seem impossible. 

 As shown, however, by the authority last quoted, a fissure-like aperture makes its 

 appearance in the indurated cuticle of the parent zooid when the embryo is ripe, 

 and through this it is gradually expressed into the outer water. A portion of the 

 endoplast of the parent animalcule, it is also shown by Biitschli, becomes separated 

 off and incorporated into the body of the ciliated embryo, while at the time of its 

 liberation it possesses also a conspicuous contractile vesicle. This latter structure 

 in the adult zooid is demonstrated by Biitschli to communicate externally through 

 the medium of a minute persistent tubular aperture. 



Professor E. Ray Lankester has recently informed the author that this interesting 

 species occurs abundantly on Gammarus pulex in the neighbourhood of Hampstead. 



GENUS XI. DENDROSOMA, Ehrenberg. 



Animalcules intimately fused with one another, and forming an erect 

 branching colony-stock or zoocaulon, or several such erect zoocaula united 

 basally by a creeping adherent stolon ; the terminations of the erect 

 branches bearing numerous capitate suctorial tentacles similar to those of 

 the ordinary Acinetidae ; the compound colony-stock increasing in size by the 

 extension of the adherent stolon and development from it of new zoocaula, 

 and by the repeated fission and outgrowth of the terminal branches ; local 

 distribution effected by the production of endogenous ciliated embryos, and 

 by exogenous gemmation ; contractile vesicles and endoplast distinctly 

 developed. Inhabiting fresh water. 



* ' Zeitschrift fur Wissenschaftliche Zoologie,' Bd. xxix. p. 270. 1877. 

 f Ibid., Bd. xxviii. p. 49, 1877. 



