POLYMASTIGINA 



39 



mercuric chloride, and coloured with iron-hsematoxylin. They show 

 distinctly the two granules which lie close together at the base of the 

 two flagella, as well as the fibrillum or rhizoblast which runs from 

 each granule sideways to the nucleus. 



B. lacertce undergoes reproduction in several ways. Round brood- 

 cysts are sometimes seen, which are formed by the secretion of a soft, 

 jelly-like membrane after complete degeneration of the flagellate 

 apparatus, and within which two to four daughter-individuals are 

 formed. During other stages of its development, the parasite multi- 

 plies, without encysting, by longitudinal fission, in the course of which 

 an equatorial plate is formed, the nuclear mechanism evidently aiming 



FIG. 7. Species of Flagellates which are parasitic in the cloaca of lizards. (After 

 Prowazek, slightly modified.) a, Bodo lacertce ; b, Trichomastix lacertce ; c, Trichomonas 

 lacertce. 



at an exact division of the chromatin. Permanent cysts are also 

 formed, by means of which infection is conveyed. These cysts are so 

 highly refractive that little is to be learnt from them in the living state. 

 Cover-glass preparations, however, when stained with iron-haematox- 

 ylin, show that autogamous reproduction takes place within them. 



Order 2. Polymastigina. 



The Polymastigina are Flagellates with one or two nuclei and with 

 four to eight flagella, the latter differing more or less in structure. In 

 the binucleate varieties, the nuclei are similar in form and size. To this 

 class belong the parasites Trichomonas and Lamblia, which differ 



