194 PROCEEDINGS OF SOCIETIES. 



process of fission, was really the result of the conjunction of 

 two infusors, which he maintained exchanged spermatic 

 elements (nucleoli). Stein now denies the exchange, but 

 maintains that the conjugation merely gives a stimulus to 

 the development of the sexual organs. Professor Huxley 

 thinks that, at first sight, Balbiani's is the more likely view. 

 The nucleus, at any rate, splits up, and each piece becomes 

 an embryo — not acting therefore like a true ovary, but in a 

 measure like the nucleus of a cell. The embryo so formed is 

 a ciliated creature, with long sucker-like pseudopodia ; it is 

 what is called the Acineta-form (fig. 3) . There are four definite 

 modifications of the Infusorian type, illustrated respectively 

 by — (1.) Paramoecium and the free forms. {2.) Vorticella 

 and the stalked forms, in which the cilia are confined to a 

 double row on the " head,^^ one row on each side the crescent- 

 shaped oval aperture. The stem of Vorticella contains a 

 true muscular fibre. No nucleoli or testes have ever been 

 detected in Vorticellse, and Stein maintains that the little 

 fellows hanging on to large Vorticellse, which used to be 

 thought "buds," are really the male forms conjugating (as do 

 two Paramsecia), and that they are ultimately absorbed into 

 the larger individual. The view which Stein put forward as 

 to the connection of Vorticella, Acineta, and Actinophrys, 

 he has now withdrawn. It is quite erroneous. (3.) Acineta 

 and Podophrys. These are most remarkable as presenting 

 permanently (?) the condition of young Infusoria. The 

 hollow sucker-like pseudopodia in them take the place of a 

 mouth. They are in fact " polystoraatous.^' (4.) Noctiluca. 

 Hackel very erroneously places this animal with his Protista. 

 It is difficult to put it any wlicre, but Pi'ofessor Huxley prefers 

 to place it here. De Quatrefages has shown that it is the 

 granules of the superficial layer that give rise to the light. 

 Noctiluca is like a reticulate monerozoon placed quite within 

 a peach-shaped capsule, to which is attached the tail-like 

 process, and in which is the mouth, its horny ring, and 

 cilium-like tongue. (See papers in this Journal by Professor 

 Huxley and others.) 



The Annuloida have their tissues differentiated into cellular 

 elements. They exhibit a Bilateral and often a successional 

 symmetry of parts (contrasting in this with Infusoria). They 

 never have a chain of ganglia. They all have the water- 

 vascular system. Two groups may be distinguished among 

 them, the Scolecida and the Echinodermata. The Rotifera 

 form a good commencement for the study of the Scolecida as 

 they present the typical structure. The cuticle of the Rotifera 

 is more or less chitinous ; the body is faintly annulated. At 



