68 



ZOOLOGY 



SECT. 



particles to penetrate into the vacuole, where they are digested. 

 In Euglena, as we have seen, there is a short, narrow gullet, and 

 in some genera (9, g) this tube becomes a large and well-marked 

 structure. 



Skeleton. While a large proportion of genera are naked or 

 covered only by a thin cuticle, a few fabricate for themselves a 

 delicate chitinoid shell or lorica (10, /.), usually vase-shaped and 

 widely open at one end so as to allow of the protrusion of the 



FIG. 48. Hsetnatococcus pluvialis. A, motile stage; B, resting stage ; C, D, two modes 

 of fission ; E, Hmnatococcus lacustris, motile stage ; F, diagram of movements of flagellum ; 

 ehr. chromatopliores ; <-. vac. contractile vacuole ; c.ic. cell- wall ; nu. nucleus; /!<<'. nucleolus ; 

 pyr. pyrenoids. (From Parker's 



contained animalcule. In the chlorophyll-containing forms there 

 is a closed cell-wall of cellulose (Fig. 48, c.v. ). 



In many genera Colonies of various forms are produced by 

 repeated budding. Some of these are singularly like a zoophyte 

 (see Sect. IV.) in general form (Fig. 47, 11}, being branched colonies 

 composed of a number of connected monads, each enclosed in 

 a little glassy lorica ; or green (chlorophyll-containing) zooids are 

 enclosed in a common gelatinous sphere, through which their 

 fiagella protrude (12) ; or tufts of zooids, reminding us of the 

 flower-heads of Acacia, are borne on a branched stem (13). In 

 Vohox (Fig. 50) the zooids of the colony are arranged in the form 

 of a hollow sphere, and in Pamlorina (Fig. 49) in that of a solid 

 sphere enclosed in a delicate shell of cellulose. Lastly, in Wiipido- 



