nucleus from ameba proteus as soon after the ingestion 

 of a Paramecium as possible. If the operation vas perform- 

 ed immediately the Paramecium wis not killed, but escaped, 

 owing doubtless to the lack of certain secretions. But even 

 when the operation was not performed until the death of the 

 Paramecium, the digestion was much more slow and incomplete 

 than normal. Hofer concludes that "protoplasm can produce 

 secretions only with the aid of the nucleus." 



Other substances than digestive secretions are no 

 longer formed after the removal of the nucleus. Thus Klebs 

 (1887) observed that when ::ells of Spirogyra virere treated 

 with strong sugar solutions, and snail globules of protonlasn 

 were formed as the result of the plasmolysis, only those 

 fragments which contained nuclei made new cellulose mem- 

 branes. Later Verworn (1888) showed that pieces of Poly- 

 stomella crispa, a protozoon which secretes about it a 

 snail shell of lime, were able to form a new shell pro- 

 vided they contained a nucleus, but the pieces which lack- 

 ed a nucleus, tho showing the normal ameboid movement, 

 were quite unable to form a new sliell. The relation of the 

 nucleus to the form.atlon of these substances is further 

 born out by the observations of Haberlandt (1887): that 

 whenever there is a localised formation of new cell wall 



(17) 



