the nucleated pieces soon forced ripw rrembranes and con- 

 tinued to live, tic 'on-nucleated pieces died withou-tlref;en- 

 erating a membrane. These observations were extended and 

 confirmed by the careful experiments of Nussbaum (1RR5). 

 With a fine needle he divided the infusoria Oxytricha and 

 Gastrostyla into a nucleated and non-nucleated piece. The 

 non-nucleated piece died in the course of a few days, 

 without any manifestation of regeneration; but the nuclear 

 part was regenerated into a complete cell, and continued 

 to grow and reproduce by division. From these experiments 

 it is evident that for the phenomena of growth and division, 

 and for the regeneration of lost parts, the nucleus is ab- 

 solutely essential: and upon these facts all subsequent 

 investigators are agreed. The observations of Gruber 

 (1884) upon Spirogyrat those of Balbiani fl8P2) and Verworn 

 (1888) upon many infusoria; those of Tofer (18^0), Stole 

 (j-QlO), and the author upon Ameba proteus: and many other 

 direct and indirect observations lead inevitably to the 

 conclusion that without the nucleus cell grov/th and cell 

 division as well as the regeneration of lost parts are 

 absolutely impossible. Wiatever additional function the 

 nucleus may have, its relation to the phenomena of growth 

 is beyond question. 



Altho there is no such uniformity of opinion with 

 regard to the part played by the nucleus in other activ- 



(11) 



