190 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Now the new species represents the “ aurelia” type as regards the 
micronnclei (two in number, and of the endosome type), while in other 
features it belongs to the “ bursaria ” group. J. A. T. 
Long-continued Pedigree Culture of ParamoBcium aurelia. — 
Lorande Loss Woodruff ( Proc . Nat. Acad. Sci., 1921, 7, 42-4). 
Reporting on Dec. 30, 1920, Woodruff notes that the culture begun in 
1907 has lasted for 13J years, exhibiting about 8,400 generations. 
Thus the conclusion is still justified that conjugation is not a 
necessary phenomenon in the life-history of Paramoecium aurelia under 
favourable environmental conditions. But the internal reorganization 
process called endomixis occurs regularly. Whether this endomixis is 
necessary for the continuance of the race is another question. J. A. T. 
Effect of Cutting during Conjugation.— Gary N. Calkins (« Journ . 
Exper. Zool., 1921, 34, 449-70, 10 figs.). Pairs of conjugating 
individuals of Uroleptus mobilis were cut across. They unite by their 
anterior ends and the free bodies extend outwards like the two arms of 
a V. A successful operation cuts the V at the apex, giving two pieces 
if the cut is in the long axis, or three pieces if it is transverse. One of 
the arms (and the apical piece if the cut is transverse) is immediately 
fixed and stained. The other arm, representing the second individual 
of the pair, is placed in fresh culture medium in the same manner as a 
normal ex-conjugant. As the processes of nuclear change are synchronous 
in the two individuals, the permanent preparation furnishes a picture of 
the nuclear apparatus with which the experimental animal starts. The 
striking general result is that although the union of nuclei in the two 
conjugating individuals is prevented, the changes go on as if the conjuga- 
tion had continued to the end. Cutting the cell and severing 
protoplasmic connexions with the second individual in conjugation 
does not stop the succession of cellular processes after they have been 
once started. The entire series of maturation and reorganization 
processes appears to be set in motion by the first contact of the 
conjugants. The experiments indicate that metamorphosis of the nuclei 
and cell is an “ all or none ” phenomenon, which once started goes 
through to the end of reorganization whether the companion cell is 
associated with it or ^ not, and with this process of reorganization is 
associated the renewal of vitality of the protoplasm and a new life- 
cycle. J. A. T. 
Consequences of Conjugation in Paramcecium.— Juljusz Zwei- 
baum ( Archiv . Protistenhunde , 1921, 44 , 99-114, 2 figs.). Experiments 
with Paramoecium caudatum show that there is a marked increase in the 
oxydation-activity after conjugation, and that this continues for four to 
five months. There is an increase in surface after conjugation (23 p.c.), 
but the oxvgen-absorption increases much more (147*5 p.c.). The 
re-organization of the macronucleus probably means a re-activation of 
the oxydation-ferments of the macronucleus. J. A. T. 
Production of Reserve Material after Conjugation. — Juljusz 
Zweibaum ( Archiv . Protistenkuude, 1922, 44 , 375-96, 2 pis.). A study 
of Paramoecium caudatum leads to the conclusion that at the time of 
