270 COPROZOIC MASTIGOPHORA 



elaborations of tlie superficial layer of the body, there occur others which 

 arise from the formation of internal structures. In Trichomonas there is 

 developed an organ called the axostyle, which is traceable through the 

 body from the region of the blepharoplasts to the posterior end, through 

 which it projects as a pointed rod. It is supposed by some to be a modified 

 axoneme (see p. 42). Similarly, in this flagellate, which possesses an 

 undulating membrane, a stiff fibre is developed along the base of the 

 membrane. In Chilomastix the edge of the cytostomal groove is rendered 

 rigid by two fibres which pass along its margins. The blepharoplast may 

 be a simple granule in which the axoneme originates, or associated with it 

 there may be another body of variable size and shape — the parabasal. 

 The parabasal and the blepharoplast may be intimately connected, as in 

 the trypanosomes and allied flagellates, to form a compound organ — the 

 kinetoplast. 



The majority of Mastigophora are uninucleated, and possess one or, 

 at most, a small number of flagella with a corresponding number of ble- 

 pharoplasts, which are usually closely grouped together, so that the indi- 

 vidual blepharoplasts may be difficult to detect. The order Hypermas- 

 tigida, however, includes flagellates which, though uninucleated, possess 

 a large number of flagella and blepharoplasts. 



The members of the order Diplomonadida {Giardia and Hexamita) have 

 two nuclei and eight flagella and blepharoplasts, while the members of the 

 order Polymonadida are multinucleate, and have a large number of flagella 

 and blepharoplasts. 



Reproduction amongst the Mastigophora is usually by binary fission, 

 the division being a longitudinal one, which commences as a rule at the 

 flagellated end of the organism after the blepharoplast and nucleus have 

 divided. This division may take place in the free-swimming condition, 

 or after the flagellate has lost its flagella and become an amoeboid or 

 rounded form, or in some cases after encystment has taken place. Cyst 

 formation as a means of protection against desiccation commonly occurs. 



COPROZOIC MASTIGOPHORA. 



As in the case of free-living amoebae, the encysted forms of many free- 

 living flagellates are able to withstand the action of the digestive fluids 

 of an animal's intestine. They pass unchanged through the intestine, 

 and liberate the flagellates in the faeces. There are thus coprozoic flagel- 

 lates as there are coprozoic amoebae. Some flagellates which live in 

 stagnant water and infusions are able to live in the intestine, especially 

 of cold-blooded animals. It is possible that the Hexamita of the frog's 

 intestine is identical with a similar form which lives in water. Berliner 



