REGENERATION OF ANTENN2—SCHMIT-JENSEN. 525 
removed together with that. In such species as have the ganglion 
opticum located nearer the brain and where it consequently is not 
injured by the removal of the eye stalk, such antenna-like regenerations 
were never obtained, but an eye was always formed to take the place 
of the one which was removed. By comparing these regenerations 
with the normal appendages, Herbst concluded that they could only 
be regarded as antenna-like formations, which in structure nearest 
resembled the first pair of antenne (the antennule). 
Herbst did not consider these peculiar regenerations to be a result 
of atavism, and founded this opinion for one thing on the result of 
the following interesting experiment: 
If the ball-shaped apex of a stalked eye in certain species of Pale- 
mon and Palinurus is removed, and the ganglion opticum is then 
pulled out through the wound by the aid of a pair of forceps, an 
antenna-like regeneration on the eye stalk results. 
Herbst believes it is thereby proved that the same cells in the stalk 
may regenerate into a new eye or into a very different structure, an 
antennula, according to whether or not it is influenced by the gang- 
lion opticum. 
In 1910 H. Przibram(7) brought together a large number of 
recorded instances of homeceosis and added a few new cases. It will 
suffice here to mention that he described and in part figured a series 
of cases in Lepidoptera (Zygena, Cucullia, Adela) and a single case 
in the coleopterous genus Prionus. He further tabulated all the 
cases, both in Crustacea and in insects, in a comprehensive schematic 
form. 
The cases which are of special interest in the present work are later 
referred to in detail in this article. 
It is of great interest to note the regularity, which Przibram pointed 
out, in the large number of apparently quite unconnected facts which 
are classed under the name homecosis. He endeavors thereby to 
give a better understanding of these phenomena and to find a basis 
for experimental work, without which it would be hardly possible to 
prove the hypotheses advanced about the formation of homeotic 
forms. 
In 1896 Wheeler(8) divided these phenomena into (a) substitu- 
tional and (6) adventitious homeosis. Przibram adopted this divi- 
sion and added a third, (c) the transpositional (translation) homeeosis. 
These three kinds of homeosis are characterized as follows: 
(a) Substitutional Homeosis.—(Wheeler: ‘‘substitutional homceo- 
sis.’ Przibram: ‘‘Ersatz H.,” substitution, Homeosis s. str.) This 
form consists in the supplanting of one appendage (‘‘Gliedmass’’) 
by another which normally belongs to a different body segment. 
