DEVELOPMENT OF THE SACCUS ENDOLYMPHATICUS 233 
which surrounds the brain and extends caudally into the verte- 
bral canal. The part lying within the vertebral canal sends out 
processes through the intervertebral foramina which come to 
lie upon the spinal ganglia (Coggi, ’90). All the different parts 
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Fig.1 Membranous labyrinth of Rana, according to Retzius (taken from 
Gaupp 96). amp.ant., ampulla anterior; amp.post., ampulla posterior; ca.sc.ant., 
canalis semicircularis anterior; ca.sc.lat., canalis semicircularis lateralis; ca.sc.- 
post., canalis semicircularis posterior; d.e., ductus endolymphaticus; lag., lagena; 
mac.sac., macula acustica sacculi; p.bas., pars basilaris; p.negl., pars neglecta; 
r.ant.N. VIII, ramus acusticus anterior;r. post. N. VIII, ramusacusticus posterior; 
rec. utr., recessus utriculi; sac., sacculus; s7. post. utr., sinus posterior utriculi; 
st. sup.ulr., sinus superior utriculi; wér., utriculus. 
of the saccus endolymphaticus are filled with a milky fluid con- 
taining many lime crystals which refract light and, according 
to Sterzi (99), exhibit brownian movement. 
My first task was the investigation of the development of the 
saccus endolymphaticus, especially in regard to its histological 
