52 THE INVERTEBRATA 



Chrysidella (Fig. 39 B). Two flagella; two yellow chromatophores ; 

 a groove anteriorly. Symbiotic in foraminifera, radiolarians, etc. 



Cyathomonas (Fig. 39 C). Two flagella; chromatophores absent. 

 Holozoic, seizing food by trichocysts in the gullet. In fresh waters. 



Chilomonas. Two flagella ; chromatophores absent ; gullet very deep 

 and narrow. Saprophytic. In foul fresh waters. 



Phaeococcus. Normally in the palmella phase. Marine and in fresh 

 waters. 



Order EUGLENOIDINA 



Phytomastigina which have numerous green chromatophores or are 

 colourless ; with reserves of paramylum and sometimes also oil ; with 

 gullet; with contractile vacuole opening by a "reservoir", usually 

 into the gullet; without transverse groove; with stout pellicle, usually 

 with metaboly ("euglenoid movement"). 



Euglena (Fig. 39 D, D'). A typical member of the group, with 

 chromatophores ; one flagellum, arising from the bottom of the gullet, 

 double at base, and connected by two rhizoplasts to a basal granule 

 behind the nucleus ; pyrenoids present only in a few species ; paramylum 

 reserves; and contractile vacuole fed by accessory vacuoles. The 

 nutrition is interesting. Most species, at least, can live and multiply, 

 with purely holophytic nutrition. All, however, flourish better if 

 traces of aminoacids be present. If the medium be rich in organic 

 substances, the use which is made of these varies with the species. 

 Most, including E. viridis, can take in organic combination nitrogen, 

 but not carbon ; a minority, including E. gracilis, can also obtain carbon 

 in that way. In the dark, if suitable compounds, especially peptones, 

 be present, the latter set of species bleach and live as saprophytes. It 

 has not been established that Euglena uses its gullet to take solid food. 

 Fresh waters, and infusions. 



Peranema (Figs. 11, 39 E). Without chromatophores; gullet sup- 

 ported by rods and can open or close. Saprophytic and holozoic. 

 Paramylum reserves formed. In infusions. 



Copromonas { = Scytomonas , Fig. 39 F, F'). Without chromato- 

 phores; body pear-shaped; no metaboly; gullet long and narrow. 

 Nutrition holozoic, chiefly by bacteria. Coprozoic in dung of frogs. 

 After some days of binary fission syngamy takes place between 

 ordinary individuals (hologamy), the nuclei first throwing out two 

 "polar bodies". Some zygotes encyst; others continue to divide. 

 Finally all encyst. The cysts are washed away and swallowed by a 

 frog or toad with its food. They pass uninjured through the gut and 

 hatch in the moist faeces, where alone the active stage exists. 



Colacium. Normally in the palmella phase, forming branched, 

 plant-like growths. 



