PLASMODROMA AND CILIOPHORA 159 



of the group Protociliata (OPALINATA) possess cilia during the whole of 

 their existence, whereas amongst the Euciliata certain forms (CI LI ATA) 

 constantly have cilia, while others (SUCTORIA) have them only in their 

 youngest free-swimming stages, which, however, soon attach themselves 

 to objects, lose their cilia, and develop suctorial tentacles. 



Multiplication amongst the Ciliophora is by binary fission or bud 

 formation. Amongst the multinucleated Protociliata nuclear division 

 proceeds somewhat irregularly, and division of the body leads to the 

 production of two daughter multinucleated individuals, which may, or 

 may not, possess an equal number of nuclei. In the case of the Euciliata, 

 which typically possess one macronucleus and one micronucleus, both 

 these nuclei divide, so that each daughter individual possesses a pair of 

 nuclei similar to that of the parent. 



From the foregoing remarks it will be seen that the phylum Protozoa 

 may be subdivided as follows: 



A. SUB-PHYLUM: PLASMODROMA DOFLEIN, 1901.— 

 Movement is effected by pseudopodia or flagella, and syngamy, where it 

 is known, takes place by the complete fusion of gametes. 



I. CLASS: RHIZOPODA VON SiEBOLD, 1845.— The predominating 

 phase is amoeboid, locomotion being effected by means of pseudopodia. 



II. CLASS: MASTIGOPHORA Diesing, 1865.— The predominat- 

 ing phase is flagellate, locomotion being effected by means of flagella. 



III. CLASS: CNIDOSPORIDIA Doflein, 1901.— Parasitic forms 

 which are frequently amoeboid, but which produce characteristic spores 

 provided with polar capsules from which long filaments can be extruded. 



IV. CLASS: SPOROZOA Leuckart, 1879.— Parasitic forms which 

 reproduce typically by schizogony, and which give rise to sporozoites 

 enclosed in resistant oocysts after syngamy has occurred. 



B. SUB-PHYLUM: CILIOPHORA DOFLEIN, 1901.— Move- 

 ment is effected by means of cilia. 



GROUP 1: PROTOCILIATA Metcalf, 1918.— There are two or more 

 nuclei, which are all of one type. Syngamy is effected by the complete 

 fusion of uninucleated gametes. 



I. CLASS: OPALINATA.— With the characters of the group. 



GROUP "1: EUCILIATA Metcalf, 1918.— There is a definite nuclear 

 dimorphism, the nuclei being of two types (macronuclei and micro- 

 nuclei). When syngamy takes place the macronuclei disintegrate, the 

 micronuclei alone taking part in the process, which is characterized 

 by the exchange of the products of division of the micronuclei between 

 two temporarily associated individuals. 



