ON THE LIFE-HISTOKY OF THE FORAMINIFERA. 127 



existence, and the microspheric form numbers of comparatively 

 small nuclei. 



Some of the apparently contradictory statements may pro- 

 bably thus be reconciled. Thus, in Textularia, while Max 

 ScHULTZE and Butschli find two, three, or more nuclei, K. 

 Hertwig finds a single one. From Butschli's figures it 

 appears that he was dealing with microspheric forms. 



The frequent occurrence of a single nucleus in the genera 

 which have been examined is in harmony with the fact that the 

 megalospheric form usually far outnumbers the microspheric. 

 It is probable, however, that the nuclear history differs to some 

 extent in different groups of Foraminifera. It may also be 

 observed that, as I shall show presently in the case of Polysto- 

 mella, bodies which I believe to be formed in the elaboration 

 of the food may possess staining properties and be thus readily 

 mistaken for nuclei. 



In Botalina and Qlohigerina, Hertwig describes the nuclei 

 as consisting of two parts, of which one is granular and takes 

 the stain, and the other is clear and homogeneous. Schulze 

 however states that the nucleus of Botalina, as seen by him, 

 resembles that of Polystomella, and this is also true of Rotalina 

 ■Beccarii (figs. 39 and 40). In Polystomella, an appearance 

 somewhat resembling that which Hertwig describes is some- 

 times presented when a vacuolar space, probably resulting from 

 the action of the reagents, lies alongside the nucleus. 



At the conclusion of his paper, Hertwig says that the Fora- 

 minifera, with one or few nuclei, would doubtless at the time of 

 reproduction become many-nucleated. Relying on the analogy 

 of the Radiolaria, with whose life history he had recently dealt 

 (18), Hertwig concluded that it is improbable that the mul- 

 tiplication of the nuclei should take place by simple fission, and 

 that a process similar to that which he had found in Thalassicola, 

 in which the originally single nucleus becomes divided into 

 .minute particles, which are distributed through the protoplasm, 

 was more to be expected. 



How correct Hertwig's surmise appears to have been will 



be seen in the sequel. 



13—2 



