60 BULLETIN OF THE 
Nitsche (’71, pp. 431, 432) our first intimate knowledge of this organ. 
He believed it to consist in the adult of Flustra of a single cell layer, 
in which are imbedded (or applied?) longitudinal and circular muscle 
fibres. He believed the kamptoderm to be formed gemmigenetically only 
by the outer cell layer, the derivative of the mesoderm. Repiachoff (’75, 
pp. 138, 139) observed in Tendra (Membranipora) “die Doppelschichtig- 
keit der Tentakelscheide nicht nur bei den jungen Knospe sondern auch 
bei den ganz ausgewachsenen, offenbar schon längst functionirenden, in 
ihrem mittleren Theile ganz braunen ‘ Polypiden,’” and later (’76, p. 152) 
a similar two-layered condition of the kamptoderm (Tentakelscheide) 
in Membranipora and Lepralia. Ehlers (76, p. 37) finds a single layer of 
cells in the kamptoderm of the adult Hypophorella (Ctenostome), which 
he believes is continuous with the endocyst of the body wall, and thus 
is ectodermal, He finds neither longitudinal nor circular muscle fibres, 
Haddon (’83, p. 517) believes the kamptoderm to be derived from both 
the inner and outer layer of the polypide bud. Vigelius (’84, pp. 33, 82) 
deScribes it as arising from the mesoderm only (Parenchymegewebe), and 
as being essentially one-layered, both longitudinal and circular muscles 
lying in this layer. Barrois (86, p. 74) derives the kamptoderm from 
the mesodermal layer only. Ostroumoff (’86*, p. 15) believes the kamp- 
toderm to be two-layered and provided with muscles ; it is in his opinion 
derived from both layers of the bud. Freese (’88, pp. 18, 19) studied 
only the adult of Membranipora. He admits the presence of muscle 
fibres, but believes the kamptoderm one-layered. Pergens (’89, p. 507) 
states only that in the Cheilostomes studied by him the tissue of the 
kamptoderm is composed “aus abgeplatteten Zellen, zwischen welchen 
Längs- und Ringmuskelfasern eingebettet sind.” Prouho (’90, p. 451) 
states that in the primary polypide of Flustrella this organ is early 
differentiated, “ et les deux couches de rudiment prennent part à sa for- 
mation.” Finally, Seeliger (90, p. 587): “Es kann danach keinem 
Zweifel unterliegen, dass die Tentakelscheide ektodermalen Ursprungs 
ist... . . Das Mesoderm erscheint auf allen gelungenen Schnitten von 
der Tentakelscheide scharf abgesetzt.” 
It is my belief that throughout the group of marine Gymnolemata, as 
in Paludicella and Phylactolsemata, the kamptoderm is derived from both 
of the two layers of the polypide bud, is provided with a strong system 
of longitudinal and a slight one of circular muscles, and contains in the 
adult two layers, or at Teast modified representatives of two layers. I 
have arrived at this conclusion from a careful study by sections of the 
following genera : Bugula, Lepralia, Escharella, Flustrella, Bowerbankia, 
