176 
SUMMARY OP CURRENT RESEARCHES RELATING TO 
orbital, (6) infra-orbital, (c) mandibular ; by the portions above tbe 
suprabranchial branches, (d) of the ramus buccalis, (e) of the glosso- 
pharyngeal, (f and g) of the first and second branches of the vagus, and 
(A) by the germ of the lateral line strictly so called. 
Derivation of the Pineal Eye.* — Mr. W. A. Locy has a preliminary 
notice on this interesting subject, of which the summary states that : — 
(1) There are preserved on the cephalic plate of Elasmobranchs 
( Squatus acanthias) at least two pairs of accessory optic vesicles. 
(2) These, taken with the primary optic vesicles, give to the embryo 
three pairs of rudimentary eyes. 
(3) The anterior pair develope into the lateral eyes, and the first 
accessory pair form the walls of the thalamencephalon, and give rise to 
the principal outgrowth from it. 
(4) The epiphysis, therefore, is double in origin, being formed from 
a united pair of accessory optic vesicles. 
(5) Since the latter are homologous with the lateral eyes, their 
derivate — the epiphysis — is also homologous with the lateral eyes. But, 
as is pointed out, the differences in their structure need explanation. 
(6) It is thought to be highly probable that the enlarged distal end 
of the epiphysis in Squalus is homologous with the pineal eye in those 
forms in which the eye is differentiated. 
Development of the Vertebral Column, f — Dr. C. Hasse publishes a 
sixth communication on this subject. This is concerned with the 
vertebral column of the Cyclostoma and of Petromyzon Jluviatilis in 
particular. There is no intercuticular layer and no cuticula sceleti 
( Elastica externa aut.), but besides the cuticula chordse ( Elastica interna 
aut.), there is a fibrous sheath formed from the cells of the chorda- 
epithelium. The Cyclostoma are thus essentially different, as regards 
vertebral column, from Elasmobranchii and Urodela ; the development 
represents a distinct type, which the Ganoids and perhaps also the 
Dipnoi have followed. 
Concerning the Gonotome.J — Prof. C. S. Minot maintains that there 
is no such thing. The word and the idea are due to van Wijhe, who 
credited Riickert with discovering that the gonads of Pristiurus were 
segmented. But Riickert made no such discovery. Minot also points 
out that the “ primitive ova ” have a very wide distribution, e. g. in the 
mesothelium of the mesentery in young Acanthias embryos, in the 
nephrotome, in the splanchnopleure of bird-embryos. In fact, under 
the title “primitive ova” are included cells which cannot form part of 
the future gonads. It is suggested that the characteristic features may 
be due to an increase of cell-sap associated, with mitosis. 
Inheritance of Acquired Characters. § — Dr. L. Reh points out, as 
has been pointed out before, that experiments as to the transmissibility 
of mutilations are not of great importance in regard to the problem of 
the inheritance of acquired characters. As far as we understand him, 
however, he does not adequately realize that the transmission of certain 
* Anat. Anzeig., ix. (1893) pp. 169-80 (5 figs.). 
t Zeitschr. f. wiss. Zool., lvii. (1893) pp. 290-305 (1 pi.). 
I Anat. Anzeig., ix. (1894) pp. 210-3 (1 fig.). 
§ Biol. Centralbl., xiv. (1894) pp. 71-5. 
