452 Infusorial Parasites of the Tasmanian White Ant. 



packed with its component corpuscles after their immersion 

 in this fluid for a short interval. 



As with the American species, Trichonympha Leidyi is 

 represented in its earlier and immature conditions by a host 

 of polymorphic forms that differ greatly in aspect from the 

 adults. The youngest observed are of an ovate contour, and 

 clothed throughout with cilia of even length. These young 

 individuals gradually increase in length until their long 

 diameter may equal or even exceed four or five times their 

 greatest breadth, the cilia in the more advanced phases being- 

 longest posteriorly, while the surface may be obliquely 

 furrowed in opposite directions. It is in connexion with this 

 transitory condition that I have observed the phenomena of 

 propagation not hitherto recorded. This is effected by a 

 process of transverse fission, division taking place towards 

 the anterior region of the body along two intersecting fur- 

 rows. The anterior of the two separated moieties assumes a 

 pyriform outline, and grows speedily to the parent shape, 

 while the posterior one retains its primitive attenuate fusi- 

 form contour, and may continue to multiply by fission. 



When placed in diluted milk the animalcules of both the 

 American and Tasmanian species of Trichonympha have been 

 observed by me to assume a fixed condition that has not 

 hitherto been described. An attachment to the surface of 

 organic substances or other convenient fulcra is then accom- 

 plished through the medium of the long fascicle of hair-like 

 cilia that are produced from their posterior extremity. These 

 cilia, intersecting one another at a short distance from the body, 

 form a sort of hollow cone, the expanded base of which 

 grasps the selected fulcrum of support after the manner of 

 an acetabulum. This habit of, as it were, anchoring them- 

 selves by their long caudal cilia was observed in both the 

 adult and immature animalcules. No trace of the structure 

 common to all higher Infusoria known as the contractile 

 vesicle has been detected in connexion with Trichonympha 

 agilis, and in the species now introduced it is, so far as I have 

 been able to ascertain, as conspicuously absent. In this 

 absence of a contractile vesicle Trichonympha assimilates 

 itself to many Opalinidge. While commenting upon the 

 apparent position of Trichonymjiha, with relation to other 

 Infusorial forms (' Manual of Infusoria,' vol. ii. p. 553), it 

 was suggested by me that, with respect to the great length 

 of its cilia and characteristic movements, it to some extent 

 resembled the multiflagellate genus Hexamita. Though the 

 more abundant evidence since adduced has sufficed to 

 demonstrate that it belongs essentially to the Holotrichous 



