61 
actually do. Since the cytod is the earliest form, all organic 
beings have sprung from it, but all but Monera have passed 
through the cell stage also, and hence in all the higher forms 
the cytod condition in the development of the individual is 
obscure, the ovum appearing first as a cell, though Amcebz, 
Gregarine, and Radiolaria reproduce by cytods. But we 
may add to what Dr. Haeckel says on this point, that if we 
trace the development of the ovarian ovum, we actually can 
and do follow it back to the cytod condition. Dr. Haeckel 
would suggest that the disappearance of the nucleus which 
certainly occurs in some ova, at the time of impregnation 
(though in others it as certainly persists), is a reversion to 
the ancestral cytod form and is to be explained in this way. 
These views give very great importance to the cell-nucleus, 
and it is well to dwell on this, since there is a tendency to 
overlook it, even to consider it an artificial product of the 
reagents used in microscopical investigation. Dr. Haeckel 
is very firm on this question; he points to a division of 
labour between nucleus and surrounding plasm, and adduces 
the observation of the nuclei in the cells of living transpa- 
rent pelagic organisms to confront those who doubt their 
living existence. On the other hand, he distinguishes two 
kinds of cytods. It is not every Plastid devoid of nucleus 
which is a cytod, for by ‘‘ degradation” or “ retrogressive 
metamorphosis” (Riickbildung), a cell may lose its nucleus- 
and is not then to be confounded with an ancestral, nucleus- 
less cytod, though like it in simplicity. It is a ‘ sham- 
cytod” or “dyscytod.” Such are the red blood-cells and 
the horny epidermic scales of mammals. Plastids and cytods 
have been elsewhere further classified by Haeckel according 
to such characters as the presence of a wall (cell-wall), &e. 
It is this modification, then, of the cell-theory, viz., the 
Plastid-theory, which gives the Monera so much interest in 
connection with the doctrines of evolution and the question of 
Abiogenesis. 
Following his remarks on the Plastid theory Haeckel gives a 
detailed account of Bathybius, fully abstracting Huxley’s 
memoir, in which its existence was first made known, pub- 
lished in this Journal in October, 1868, and adding an account 
of his own researches. The protoplasmic network of Bathy- 
bius is considered by Haeckel apart from the coccoliths with 
which it is often densely studded, but of which it is sometimes 
destitute. He points out that the separate “cytods” of 
Bathybius average about ‘08 of a millimetre in diameter, reach- 
ing ‘1 of a millimetre, and their protoplasm is spread out in 
ramifying branches as in many myxomycetes (PI. V, fig. 5), 
