252 Proceedings of the Royal Physical Society. 



see their beautifully chambered shells imitating some of the 

 most graceful objects of nature and art, — the living streams 

 of nearly fluid sarcode, of which they are composed, flowing 

 forth from the almost invisible pores of their shells, uniting 

 with each other, and forming glairy masses, and reticula- 

 tions, and expansions, which absorb animal matter coming 

 in contact with them, — single and compound animals build- 

 ing their aggregated homes in the most graceful lines and 

 spirals, — single dwellings and populous towns slowly moving 

 along, of which the inhabitants are but patches of transpa- 

 rent slime, — vast Polythalamian cities, where the huge pri- 

 mordial Ehizopods reign, surrounded by the multitudes of 

 their dwarfed descendants, in widening circles and triple tiers. 

 Such is Ehizopod life. At present no true generative ele- 

 ments have been recorded as discovered in the Ehizopods, 

 though Carpenter and Schultze have noticed bodies which 

 they have suspected to be ova. In the autumn of 1859 I 

 was preparing a number of specimens of Hydractinia for the 

 microscope. They were first soaked in whisky for several 

 weeks, then immersed in dilute nitric acid to remove them 

 from the crab's shell, and finally washed in strong spirit, 

 and put up in Canada balsam. On examining one of these 

 preparations under the microscope, it was found that two 

 specimens of Truncatulina had been accidentally prepared 

 at the same time. The development of Truncatulina com- 

 mences with a single cell ; this multiplies by gemmation in 

 series until a colony of animals is formed, each larger than 

 its predecessor, arranged in a spiral, somewhat resembling 

 the shell of the Nautilus. In the Nautilus, the last chamber 

 of the shell only is occupied ; but in Truncatulina every 

 chamber contains its tenant, while the whole colony are 

 united by a band of sarcode, which passes from chamber to 

 chamber along the inner curvature of the shell. All the 

 cells or houses in this Ehizopod town are full of minute 

 pores, from which the inhabitants protrude their delicate 

 arms of slime in search of prey, or to move the assemblage 

 from place to place. When the Truncatulina is treated as 

 before mentioned, the shell is removed, and the sejDarate 

 zooids appear united by their connecting band. One of the 



