6 NATURAL SCIENCE. July. 



published an *' Etude preliminaire "{Bull. Soc. roy. Malac. Belgique, vol. 

 xxviii.), and an " Etude sur le Dimorphisme des Foraminiferes et des 

 Nummulites en particulier " {Bull. Soc. Beige Geol., vol. vii.). The latter 

 is an elaborate paper of 41 pages, and discusses at length the views of 

 Hantken,DelaHarpe,'Munier-ChalmasandSchlumberger,Tournouer, 

 Fischer, and others, and states the following conclusions : — A . That 

 dimorphism in the Foraniinifera is met with in all types where con- 

 ditions of life are favourable to existence. B. Dimorphism is *' of 

 absolutely initial origin and in relation with the origin of life itself." 

 C. The characteristic of dimorphism in the Foraminifera is, as a 

 general rule, furnished by the contrast existing between the dimensions 

 of a section of the adult of two forms of the same species, and the 

 dimensions in an inverse sense, and infinitely more accentuated, of the 

 section of the central or initial chamber. D. From the similarity of 

 external characters, etc., it is easy to assure oneself that the two forms 

 A . and B. not only belong to the same group or zoological subdivision 

 of one genus, but even to the same species. E. As to the difference 

 in shape of the two forms in the adult state, the character of the 

 spire, form and number of chambers, they never present but secondary 

 variations. F. The difference of the initial stage appears due to 

 the fact that the Foraminifera repvodnce themselves by two distinct processes 

 {fission and gemmation) [previously pointed out by Fischer (1870) and 

 Dollfus (1890); see M. Van den Broeck's paper, p. 15] . G. Gemma- 

 tion is well-known among the Foraminifera, Fission among the Fresh- 

 water Rhizopoda. The shells of Foraminifera may be a true colony, 

 of which the individual of each successive chamber may, by a kind 

 of fission, be the product of the division of the preceding, remaining 

 attached to the colonial skeleton by a non-liberated test. H. Whether 

 the differential characters noticed in the dimorphous tests are con- 

 nected with the shape and disposition of the chambers or the external 

 characters, or whether these characters are connected with the spire, 

 form, number, or grouping of the chambers in the forms A. and 5. of 

 the same species, or even the respective abundance of A. and B. in the 

 same habitat, we ought to state, in favour of the principle of initial 

 dimorphism, that these differential characters find, without trouble or 

 argument, their raison d'etre precisely in the natural consequences of initial 

 dimorphism, due to the contrast in the reproductive processes. /. The 

 sole objection that may be opposed to this interpretation, consists in 

 the fact that to justify two initial forms in the same species it is 

 necessary to prove — which does not yet appear to have been fully done 

 — the existence of embryonic stages or at least young individuals show- 

 ing, diSmA. and B., large and adult forms, the divergence into mega- 

 sphere and microsphere of the initial chambers. J. One may be 

 able reasonably to add to the phenomenon of expulsion, setting 

 aside the last external chambers of Nummulites, the fact that never 

 has anyone noticed or figured an adult Nummulite, entire and intact, 

 showing a mouth or opening perfectly preserved. K. Looking at the 



