STEUCTUEE AND EEPEODUCTION 



23 



nucleolus was found, but there were often as many 

 as twenty or more in full-grown specimens. Schulze 

 also noticed that the nucleus occupies a position in 

 the middle third of the series of chambers, and often 

 lies partly in one of the narrow canals connecting the 

 chambers, being preserved in its progress from one 

 chamber to another. The position of the nucleus is 



r 



X230 



Fig. 14. 



1. Nucleus of Polystomella crispa (L.), megalospheric form. 2. Nucleus with larj^e 

 vacuolated nucleolus, in P. crispa. 3. Nucleus of same species, which has lost 

 its rounded form, lying within four segments. 4. Nucleus of a megalospheric 

 specimen of ilotalia Btccarii. After Lister. 



thus dependent on the number of chambers in the 

 individual ^ (fig. 16). 



That the presence of a nucleus is essential for the 

 (jroivth and reproduction of the animal is proved by 

 such observations as that of Yerworn, who broke up 

 a specimen of Polj/stoviellu, the larger pieces re- 

 maining alive, as shown by their extended pseudo- 



' For further details of observations on the nucleus of the Foraminifera 

 see Lister, l']iil. Trans. Boy. Svc. vol. 186b, 1895, pp. 401-453. 



