82 CLASSIFICATION OF MEDUSA. 
Dalyell, and supported by Kolliker. Dr. Johnston maintained the same view of their nature. 
Steenstrup struck out a most original and distinct speculation, holdmg them to be alternate 
generations, produced by gemmation from a dissimilar parent, and producing eggs from which 
should spring dissimilar children. 
In all instances where a Medusa has been observed originating from a hydroid polype, 
the new animal bears the closest resemblance to a naked-eyed Medusa,—a resemblance not 
merely of external form, but also of internal structure. Indeed, in many cases it would be 
impossible to draw a line between the two. 
Is it desirable to draw such a line? Are not the so-called Zoophytes and Medusz animals 
of the same section? Discoveries exactly comparable, and still more wonderful, have shown 
that the higher Meduse themselves afford instances of parallel phenomena. We now know for 
certain—all the stages of the history having been demonstrated—through the researches of 
Sars, Dalyell, Siebold, Steenstrup, Price, and Reid, that the ova of the covered-eyed Meduse, 
belonging to the genera 4urelia, Chrysaora, and Cyanea, give rise to polypoid animals, which 
in their turn originate individual Medusze by fission—or, more properly, as Dr. Carpenter 
has well suggested, by a peculiar process of gemmation. The higher genera of Discophore, 
therefore, are closely linked, anatomically and physiologically, with the Anthoxoa hydroida 
among the polypes. Assuredly any separation of such nearly allied animals, especially the 
placing of them in different classes, is exceedingly unnatural. 
In what light are we to regard the relationship between the Medusa and the Polype? The 
one is not the larva of the other, as often improperly said, because there is no metamorphosis 
of the one into the other. The first is the parent of the last, and the last of the first, but neither 
is a stage of an individual’s existence destined to begin life as a Medusa and end it a Polype, 
and vice versd. The notion that the Medusoid of the Campanularia, or Coryne, or Tubularia, 
fixes itself, and changes into the typical forms of those zoophytic groups, is as inadmissible as 
the supposition that the hydroid product of the Aurelia is metamorphosed into a Medusa of 
that genus. Facts show that such is not the case. These facts may be summed, in the 
abstract, in the following formule :— 
Ist. The case of Tubularia and Campanularia. 
a. The medusoid produces eggs. 
b. The eggs produce infusoria. 
c. The infusoria fix and become polypidoms. 
d. The polypes of these polypidoms produce medusoids. 
2d. The case of Aurelia, §c. 
a. The medusa produces eggs. 
b. The eggs produce infusoria. 
c. The infusoria fix and become hydroid polypes. 
d. The hydroid polypes produce medusee by gemmation. 
