184 DR. CARPENTER'S RESEARCHES ON THE FORAMIN1FERA. 



containing a most complete Bibliography, that I do not feel it necessary to offer more 

 than a mere sketch, marking out the principal periods into which this History may 

 be divided. 



Thejirst period includes all the observations made and published in regard to these 

 minute polythalamous bodies, from the time when they first attracted attention, down 

 to the date (1825) when M. D'ORBIGNY grouped them together, as constituting a 

 distinct type of structure. The observers whose labours during this period did most 

 to prepare the way for their successors, were SOLUANI*. FICHTEL and MOLL-J-, Mois 7 - 

 TAGUE^:, and DENVS DE MONTFORT^. 



The second period commences with the presentation to the Academic des Sciences, 

 in 1825, of M. D'ORBIGNY'S " Tableau Me"thodique de la Classe des Cephalopodes ;" in 

 which he first separated these chambered shells, under the title of Foraminifera, from 

 the Siphonifera ; still retaining the former, however, like the latter, as an order of 

 Cephalopods. A large number of new forms were added by M. D'ORBIGNY to the list 

 of those previously known ; and he laid the basis of the classification which he has since 

 more fully elaborated. No suspicion appears then to have crossed his mind, that 

 the place of these bodies might be amongst the lowest, instead of among the highest, 

 of the Invertebrata ; and if his determination of their Molluscous nature was based 

 on any actual observations of these animals in their living state, it is certain that 

 such observations must have been of the most superficial character. 



The third period, with which our knowledge of the true nature of the Foraminifera 

 really commenced, is inaugurated by the discovery, first announced by M. DUJARDIN 

 to the Academic des Sciences in June 1835, of the Rhizopodous nature of the animal 

 of certain simple forms of Foraminifera, and, by inference, therefore, of that of the 

 group generally ; and in the following year he demonstrated the essential identity 

 between the Amoeba and other simple freshwater Rhizopods (described by Professor 

 EHRENBERG among the Polygastric Animalcules) and the Crlstellaria and similar 

 composite forms of marine Foraminifera, which had been previously ranked among 

 Cephalopod Mollusks||. 



The general results of M. DUJARDIN'S observations was, that the animal body con- 

 sists, in every instance, of a mass of sarcode, a gelatinous, somewhat granular sub- 

 stance, not enclosed in a distinct membrane, and capable of extending itself into 

 threads of extreme tenuity ; that there is neither mouth nor digestive cavity, but that 

 alimentary particles, received into the very substance of the body, are gradually 

 incorporated with it ; and that both the introduction of these particles, and the move- 



* Saggio orittographico, overo osservazioni sopra la terra Nautiliche e Ammonitiche della Toscana. Sienne, 

 1780. 



t Testacea microscopica aliaque minuta ex generibus Argonauta et Nautilus, ad naturam picta et descripta. 

 Vindob. 1798, 1803. 



t Testacea Britannica, or Natural History of British Shells. London, 1803-1808. 



$ Conchyologie Systematique. Paris, 1808. 



|| See Annales des Sciences Naturelles, 2 se>., Zool. torn. iii. p. 312. 



