Frenzel’s Mesozoon Salinelia. 469 
and the two daughter individuals are, although less separated 
than they subsequently become, already present before the 
nucleus has divided. 
THE NUCLEUS OF THE PARENT INDIVIDUAL WHICH REMAINS 
UNDIVIDED BELONGS TO NEITHER OF THE DAUGHTER INDI- 
VIDUALS; THE LATTER ARE THEREFORE IN THE STAGE OF THE 
NON-NUCLEATE PROTOBLAST. But since, for the FULL 
ACTIVITY of the Protoblast, the nucleus has become an organ 
of already indispensable importance, they must in the onto- 
geny receive a nucleus much earlier than may have been the 
case in the phylogeny. The appearance of important organs 
relatively earlier in ontogeny than in phylogeny is an occur- 
rence which has indeed met with general acceptation since 
the writings of Fritz Miller. The unappropriated parent 
nucleus, which is left behind, is the more unable to lead an 
independent life, and relapses into its constructive parts: the 
daughter individuals hasten to divide among themselves this’ 
material, which is so important for the building-up of their 
further organization, and to construct from it a nucleus for 
themselves, after the pattern of that of the parent form. 
CONSEQUENTLY THE OBJECT ALSO OF THE’ MORE OR LESS 
COMPLICATED FORMS OF NUCLEAR DIVISION APPEARS TO BE 
NOTHING FURTHER THAN AN ONTOGENETIC ABBREVIATION OF 
THE PHYLOGENETIC PROCESS OF THE FORMATION OF THE 
NUCLEUS FROM THE MATERIAL SUBSTRATUM, TO WHICH THE 
HEREDITARY SPECIAL PROPERTIES ARE UNITED. ‘THIS SUB- 
STRATUM, THOUGH NOT AS YET CONCENTRATED IN THE SHAPE 
OF THE NUCLEUS, AN ORGAN SUBSEQUENTLY SO IMPORTANT, 
CERTAINLY BELONGED ALSO TO THE NON-NUCLEATE STAGE 
IN THE PHYLOGENY *. Since, therefore, the nucleus, although 
as an organ more important than ever, has been to a certain 
extent dethroned, the Protoblast without a nucleus, no matter 
whether or not there still exist non-nucleate forms capable of 
independent life, may assume its rights once more. 
The non-nucleate Protoblast, therefore, as the initial stage 
* The further circumstance that daughter-cells which have been produced 
by simple fission do not (or less frequently) form other organs also (chro- 
matophores, vacuoles in plants, circlets of cilia, collars, &c. in Protozoa) 
quite afresh by themselves, but acquire them by division of the organs in 
question belonging to the parent-cell, must, I consider, likewise be re- 
garded as an ontogenetic abbreviation of the original process of the origin 
of those organs. In cases, however, where the ontogeny of the cell repro- 
duces its phylogeny more faithfully, e. g. in the development of unicellular 
and multicellular creatures from spores, the organs of the parent-cell, with 
a view to formation of spores, degenerate before division takes place, and 
the daughter-cells or their successors are obliged to reconstruct these 
organs, with the exception of the nucleus, afresh for themselves. 
