312 Prof. M. Schultze on the Organization. 



two genera named in remarkable abundance) he frequently found 

 Orbulina, each of which contained a Globigerina in its interior. 

 And a confirmation of this occurrence was communicated to me 

 by Dr. August Krohn, who, without knowing of the observations 

 of Pourtales, saw exactly the same thing in Madeira, and, indeed, 

 in living Orbulina captured at the surface of the sea in a 

 muslin net. 



Now as the one larger orifiice of the OrZ'w/ma-shell, which 

 both Ehrenberg and D'Orbigny regard as something constant, 

 is scarcely largo enough, even according to Ehrenberg, for 

 a Globigerina with a whole lot of chambers and long spinous 

 processes of the shell (which, according to Pourtales, reach to 

 the inner surface of the Or^w/ma-shell) to walk into it, and 

 immigration in a young state and development in the Orbulina 

 in the manner of the Gall-flies is unheard of amongst the 

 Polythalamia, and extremely improbable, considering the un- 

 doubted and, as proved by the structure of the shell, close 

 relationship of the two genera, the Globigerina, as both Pour- 

 tales and Krohn believe, will have been produced within the 

 Orbulina. Pourtales does not discuss any further developmental 

 connexion between the two. To me the supposition appears 

 most probable that the last chamber of the Globigerina, when it 

 has attained a certain age and size, separates like the proglottis 

 of a Tcenia, and after living in a free state for a longer or 

 shorter period, effects the reproduction. In this way the Glo- 

 bigerina is produced in its interior. 



That Polythalamia bear living young which resemble the 

 parent, I have proved from Gervais's first communications on a 

 Miliolide*. I have recently observed the same mode of repro- 

 duction in several specimens of a llotalide, as I will describe 

 below. Ordinarily, it appears, the reproduction of the Poly- 

 thalamia — the birth of living young — takes place without the in- 

 dividual chambers becoming independent. In the Globigerina, 

 however, whose globular chambers can only touch each other by 

 a small part of the surface of the sphere, and in which, no doubt, 

 a separation may very readily occur even by mechanical causes, 

 the isolation of one or more chambers appears to precede the 

 reproduction. Considering the perfectly similar structure of the 

 shells of Orbulina and Globigerina, I regard this explanation of 

 the singular discovery of Pourtales and Krohn to be the simplest 

 and most natural. 



On the supposition of a derivation of the Orbulina from the 

 Globigerina, Ehrenberg also is justified with regard to the larger 

 opening of the Orbulina-shell. As the chambers of the Globi- 

 gerina, as of the Rotalida, communicate by a large orifice, the 

 * Muller's Archiv, 1856, p. 165. 



