°4 
Immortality of the Protozoa. 
[April, 
V. A CONTRIBUTION TO THE QUES 1 ION OF 
THE IMMORTALITY OF THE PROTOZOA. 
ffTROF AUGUST WEISMANN has recently given, 
13 in the “Biolog. Central-Blatt ” (vol. iv., pp. 650 and 
and 677) a summary of his views on the life of mono- 
r ell alar animals. He concludes that t . . 
1. The controversy whether it is proper in cases o 
fission of Protozoa to pronounce mother and daughter 
one and the same individual, or as distinfl beings, is a 
mere logomachy. It has a deeper meaning only when 
we recognise that in these monocellular beings theie is n 
"indiXl” in the same sense as in the higher o = . ; 
Indeed our abstraftions-such as ‘‘ generation, mothe^ 
" daughter”— are not at once universally applicable, as 
they are artificial concepts, and not things existing 
N 2 U The idea of a “ senescence” of monocellular animals 
is not tenable. Physiologically speaking there is a profound 
difference between the monocellular and the polycellulai 
animals, in the faft that the latter only wear themselves out 
fiv living and proceed to a natural death, lne mono 
cellular animals are never so modified by the transformation 
of matter that life becomes impossible. The monocellulais 
have no physiological death ; their bodies are immoital. 
o Conjugation in the monocellulars and the piocess o 
fecundation in the polycellulars are analogous piocesses, 
and cannot be regard as processes of rejuvenescence in 
the sense of an avoidance of physiological death. This 
latter occupies a quite different place in ontogenesis, and has 
nothing in common with these processes. 
. mhe body of the monocellulars corresponds to the 
eerm-cells of the polycellulars. The sexual propagation of 
the latter may, with certain limitations, be viewed as an 
alternation of generations. We have first a generation of 
monocellular beings,— the germ-cells,— and next a generation 
of metazoic individuals, which again ™P^ uce - a n °"; 
pviiol manner a generation of monocellulais. Hie state 
of the case is more accurately represented by the conception 
[hat we here before us an infinite senes of mono 
cellulars, the germ-cells, each generation of which .splits off 
a metazoic individual or produces it as a bud. At any late 
