366 ADOLPH R. RINGOEN 
With reference to the formation of the gland lumen, I find 
that it arises in the manner described by Peterson. The early 
formation of it is frequently seen as a slight indentation on the 
free surface of a well-defined gland rudiment, shortly after it 
has pushed out into the underlying mesodermic tissue. The 
further extension of the gland rudiment is followed by a similar 
extension of the gland lumen. As to whether the extension 
of the lumen into the fundic portion is responsible for the shift- 
ing movements of the cells, I am unable to say. At all events 
the extension of the lumen into the fundic portion of the glands 
does not cause the cells there to take on a ‘schriage’ position 
with reference to the lumen, as Peterson maintains I have 
already pointed out that in the fully differentiated gastric gland 
the cells at the fundic portion are placed at right angles to the 
lumen of the gland with reference to their long axes. 
In spite of his observations relative to the origin of gastric 
glands in selachians, Peterson is at a loss to account for the 
great numbers of these structures that he finds in old specimens. 
To quote from his paper: 
Wie erfolgt nun die weitere Vermehrung der Driisen? Bei einem 
jungen Tiere hat die Schleimhaut dasselbe Aussehen wie bei einem 
alten. Es kommen genau so viel Driisen auf den Quadratmillimeter; 
auf einer Schnittstrecke von 1mm. (Schnittdicke 10 uw) liegen quer- 
wie lingsgeschnitten 20 Schnitte 1m Durchschnitt, also 400 auf den 
Quadratmillimeter. Ein Magen eines jungen Tieres (Magenlinge 
5em.) habe n qmm Fliche, der eines alten (Magenlinge 10 cm.) 
sagen wir dann 4 n qmn Flaiche, so kommen auf den einen Magen 
400 n, auf den anderen 1600 n Driisen, wo kommen diese 1200 n 
weiteren Driisen her? 
In order to account for these 1200 new glands Peterson thinks 
that there may be a longitudinal splitting of the young glands. 
As a result of this cleavage process there are now two glands 
where before there was only one. He also thinks that ‘ Ver- 
zweigungen der Driise in den mittleren Partien kénnten als 
Anhaltspunkt dienen”’ for increasing the numbers of the glands. 
Furthermore, Peterson thinks that the neck cells of a young 
gland may contribute to the formation of additional glands: 
‘Sie haben wir oben als indifferente Reste der alten Anlage 
