432 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
probable, owing to the layers of the flattened cells 
with fibrils and prominent walls that the appearance 
of a membrane, called by Patten the suspensory ligament, 
arose. No definite membrane can be seen by Schreimer 
or myself. 
The lens hes suspended in a space which has been 
termed a blood sinus, as blood corpuscles are occasionally 
found. This space, which is situated between the retina 
and the lens, like the chamber in the vertebrate eye con- 
taining the ‘‘ vitreous humour,” does not appear to have 
any connection with the lacunae of the eye stalk. I have 
found blood corpuscles only present in very few out of a 
ereat many sections, and these were probably abnormal 
occurrences due to fixation only, and the space cannot, 
therefore, be looked upon as a blood sinus. 
The Septum.—The portion of the optic vesicle con- 
taining the retina is separated from the lens chamber by 
a membrane which runs completely across the eye. This 
is the Septal Membrane (fig. 29, Sep.). Commonly the 
retinal surface of the lens lies against it. Patten, however, 
considers it a support for the lens to which it is actually 
attached, and, further, that it plays the part of an elastic 
cushion elevating the lens when it has been pulled in by 
contraction of muscle fibres. 
Owing to the retina being pulled away from its under- 
lying layers in sections, the septum comes perhaps to 
touch the lens, but in the natural conditions the lens and 
septum are not attached, and the latter can thus not act as 
an elevator. Moreover, the whole appearance of the eye 
and its reactions to stimuli render it extremely improbable 
that it possesses any means of accommodation or focussing. 
The septum in the adult appears structureless, 
thickest in the middle, where it is perforated by the 
onter branch of the optic nerve. At this place the septum 
