Miscellaneous. 229 
them, to the exclusion of every individual peculiarity, which passes 
away with them, and that therefore, while individuals alone have a 
material existence, species, genera, families, orders, classes, and 
branches of the animal kingdom exist only as categories of thought in 
the Supreme Intelligence, but, as such, have as truly an independent 
existence and are as unvarying as thought itself after it has once been 
expressed ? 
Returning, after this digression, to the question of individuality 
among Acalephs, we meet here phenomena far more complicated than 
among higher animals. Individuality, as far as it depends upon 
material isolation, is complete and absolute in all the higher animals, 
and there maintained by genetic transmission, generation after genera- 
tion. Individuality, in that sense, exists only in comparatively few 
of the Radiates. Among Acalephs it is ascertained only for the 
Ctenophore and some Discophore. In others, the individuals born 
from eggs end by dividing into a number of distinct individuals. In 
others still, the successive individuals derived from a primary one 
remain connected to form compound communities. We must there- 
fore distinguish different kinds and different degrees of individuality, 
and may call hereditary individuality that kind of independent 
existence manifested in the successive evolutions of a single egg, pro- 
ducing a single individual, as is observed in all the higher animals. 
We may call derivative or consecutive individuality that kind of 
independence resulting from an individualization of parts of the pro- 
duct of a single egg. We have derivative individuals among the 
Nudibranchiate Mollusks, whose eggs produce singly, by a process of 
complete segmentation, several independent individuals. We observe 
a similar phenomenon among those Acalephs the young of which 
(Scyphistoma) ends in producing, by transverse division (Strobila), 
a number of independent free Medusee (Ephyre). We have it also 
among the Hydroids which produce free Meduse. Next, we must 
distinguish secondary individuality, which is inherent to those indi- 
viduals arising as buds from other individuals, and remaining con- 
nected with them. This condition prevails in all the immovable 
Polyparia and Hydraria: and I say intentionally, in the immovable 
ones ; for, in the movable communities, such as Renilla, Pennatula, 
&c., among Polyps, and all the Siphonophorz among Acalephs, we 
must still further distinguish another kind of individuality, which I 
know not how to call properly, unless the name of complex individu- 
ality may be applied to it. In complex individuality a new element 
is introduced, that is not noticeable in the former case. The indi- 
viduals of the community are not only connected together, but, under 
given circumstances, they act together as if they were one individual, 
while at the same time each individual may perform acts of its own. 
As to the specific differences observed among Acalephs, there is as 
great a diversity between them as between their individuals. In some 
types of this class the species are very uniform,—all the individuals 
belonging to one and the same species resembling one another very 
closely, and exhibiting hardly any difference among themselves, 
except such as arises from age. This identity of the individuals of 
