843 THE ANIMAL KINGDOM. 



striated, and when thick of considerable resistance. Special cuticular 

 structures occur as peduncles or envelopes either gelatinous or mem- 

 branous. A peduncle secreted by the hinder end of the body, solid, stiff 

 and branched, is seen in Dendromonas and Anthophysa among Monadina, 

 secreted by the anterior end by which the animal fixes itself in Chlo- 

 rangium, and the Euglenid Colacium where it becomes branched 1 . A 

 gelatinous envelope is formed in many instances under conditions un- 

 favourable to the organism ; it occurs normally in Mas tig amoeba verrucosa, 

 and as a common investment to the colonies of Uroglena, Spongomonas, 

 Syncrypta and Colacium, or as a branched tubular structure, the individuals 

 inhabiting the ends of the tubes, in Cladomonas and Rhipidodendron. The 

 membranous envelope has two forms. In the first, it may invest the body 

 loosely as in Haematococcus and Volvox, but more usually closely as in the 

 Euglenid Trackelomonas, the Chlamydomadina and Volvocina. In the 

 two latter it is pierced by holes for the passage of the two flagella, and in 

 Volvocina the colony has a special gelatinoid (?) investment as well. The 

 second form is more or less cup-like, homogeneous, transparent, colourless 

 or brownish, with a large cavity and wide mouth ; it is seen in some 

 Monads, e. g. Codonoeca> Bicosoeca, Dinobryon some Isomastigoda> e. g. 

 Epipyxis. Dinobryon is free, Epipyxis fixed by the end of the shell, the 

 others by a peduncle. In Bicosoeca, Dinobryon, and Epipyxis a delicate 

 contractile basal thread connects the animal to the cup. Coccomonas 

 among Chlamydomonads has a shell which readily breaks into two parts, 

 Phacotus a lens-like bivalved shell. The envelope is composed of cellulose 

 in Chlamydomonas and Haematococcus ; in others of an unknown substance 

 which dissolves spontaneously in water to set free the products of fission. 



The colourless Flagellata are for the most part holozoic. Food may 

 be captured by means of pseudopodia, or by a process formed for the 

 purpose containing a vacuole, as in many Monadina and probably some 

 other small forms, or it enters by a distinct aperture near the base of the 

 flagella. A mouth in the same position with an oesophageal tube is 

 present in Euglenoids, some Heteromastigoda, in Chilomonas, and Crypto- 

 monas. In many Euglenoids, however, it serves as an outlet for the 

 contractile vacuole and is not used for purposes of nutrition 2 . Where 

 chromatophores are present, the organism is holophytic : some colourless 

 forms related to or derived from coloured are saprophytic 3 . Food 



1 The old stems of Anthophysa become brown ; the granules visible in the substance of the 

 young stem appear to be of an excretory nature. In an animal fed with indigo or carmine the 

 particles of this pigment are soon excreted, and stored up in the newly formed portion of 

 the stem. 



2 Kent states (Manual of the Infusoria, p. 380) that he observed not only accumulations of 

 particles of carmine in the body of Euglena viridis when that animal was kept in water, containing 

 in suspension finely pulverized carmine, but also the entrance of particles at the anterior extremity 

 of the oesophagus. 



3 The ingestion of solid food by a coloured form Chromulina (Chrysomonas) fiavicans is 



