92 ,. ZOOLOGY SECT. 



stalk of VortMla. Infusors and other organisms are caught by 

 the tentacles (4, 6), the cuticle of the prey is pierced or dissolved 

 where the sucker touches it, and the semi-fluid protoplasm can 

 then be seen flowing down the tentacle into the body of the 

 captor. A single tentacle only may be present (3), or the tentacle 

 may be branched (4), the extremity of each branch being suc- 

 torial. In some forms there are no terminal suckers (J), and the , 

 tentacles are waved about to catch the prey instead of standing 

 out stiffly as in Acineta. In other cases there are one or more 

 long striated tentacles with tufted ends (7). 



The nucleus may be ovoid (la), horseshoe-shaped, or branched 

 (#, 9) : in some cases a micronucleus (1 a, mi. nu.) has been found. 

 There are one or more contractile vacuoles (c. vac,). 



Some genera are naked (./) : others form a stalked shell or 

 lorica (3 a) like that met with in many of the Mastigophora. 



The only colonial form is the wonderful Dendrowma (9), in 

 which the entire colony attains a length of about 2 mm., and bears 

 an extraordinary resemblance to a zoophyte (vide infra, Sect. IV.). 

 It consists of a creeping stem from which vertical bra'nches spring, 

 .and the various ramifications of these are terminated in Podo- 

 phrya-like zooids with suctorial tentacles. The nucleus is very 

 remarkable, extending as a branched axis throughout the 

 colony (b, nu.). 



Reproduction by Unary fission takes place in many species. 

 In Ephclota gemmipara (8) a peculiar process of budding occurs : 

 the distal end of the organism grows out into a number of pro- 

 jections or buds, into which branches of the nucleus extend. These 

 become detached, acquire cilia on one surface, and swim off' . (b). 

 After a short active existence tentacles appear and the cilia are 

 lost. In this case budding is external, but in Acineta tiiberosa (2 b) 

 the buds become sunk in a depression, which is finally converted 

 into a closed brood-cavity (b,c.) : in this the buds take on the form 

 of ciliated embryos, which finally escape from the parent. In 

 Dcndrosoma the common stem of the colony produces both internal 

 and external buds (b, Id.). 



further Remarks on the Protozoa. 



The majority of the Protozoa are aquatic, the phylum being 

 equally well represented in fresh and salt water. They occur 

 practically at all heights and depths, from 8,000 to 10,000 feet 

 above sea-level, to a depth of 2,000 to 3,000 fathoms. Some 

 forms, such as species of Amoeba and Gromia, live in damp sand 

 and moss, and may therefore be almost considered as terrestrial 

 organisms. In accordance with their small size and the readiness 

 with which they are transported from place to place a large pro- 

 portion of genera arid even of species are universally distributed, 



