ENCYSTATION OF ACTINOSPHHRIUM EICHHORNI. 421 
He speaks of nuclear out-thrust as occurring only “very 
abnormally” in the reduction in the mother-cyst. From 
what I have seen in my cultures I believe that, though cer- 
tainly not quite normal, such out-thrust methods tend to come 
into play very quickly as partial substitute for a weakened 
power of nuclear elimination by the usual method. In all my 
cultures, except B9 warm, I met with out-thrust unabsorbed 
nuclei till a certain stage in the degeneration was reached, 
when even this more drastic measure seemed unavailable, 
and the nuclei died off in the mother-cyst, remaining there 
unabsorbed until the whole gradually disintegrated. 
I wish to express my warm thanks to Professor Hertwig 
and his assistants for their unfailing readiness with advice 
and practical help during my work in Munich; and also to 
Miss Boissevain for her many valuable suggestions and 
personal assistance. 
ManiscHaL CoLurcs, 
ABERDEEN. 
December, 1907. 
Inpex OF REFERENCE LITERATURE. 
1898. Hertwic, R.—‘ Uber Kernteilung, Richtungs-Kérperbildung, und 
Befruchtung von Actinosphaerium eichhorni.’ 
1900. “Uber Physiologische Degeneration bei Protozoen,” ‘Sitz.- 
Ber. d. Kel. bayr. Akad. Wiss.,’ Bd. 32, Heft 1. 
1902 and 1903. “ Uber das Wechselverhiiltnis von Kern und Proto- 
plasma,” ‘ Sitz.-Ber. d. Gesell. f. Morph. u. Phys.,’ Minchen, 1st 
November, 1902, and 19th May, 1903. 
1903. “ Uber Korrelation von Zell und Kerngrosse und ihre Bedeu- 
tung fiir die geschlechtliche Differenzierung und die Teilung der 
Zelle,” ‘ Biol. Centralbl.,’ Bd. xxi, Nr. 2. 
1904. “Uber Physiologische Degeneration bei Actinosphaerium 
eichhorni,” ‘ Festschr. ftir Haeckel,’ Jena (G. Fischer). 
1905. ‘Uber das Problem der sexuellen Differenzierung,”’ ‘ Vert. d. 
deutsch. Zool. Geo. in Breslau.’ 
1906. “Uber die Ursache des Todes.” Offent. Vort., 7th December 
‘All. Zte.,’ Nr, 288, 289. 
VOL. 52, PART 3.—NEW SERIES. 32 
