60 JOURNAL OF THE 
ing. In the teleost forms studied by Mitrophanow (spe- 
cies not stated) the anlage develops in same way as in 
Serranus—as a furrow. 
The salmon egg is very different from that of Serranus. 
It is large, and with relatively firm yolk. At my sug- 
gestion Mr. J. E. Mattocks undertook the problem of 
ascertaining in the first place, whether the common anlage 
existed in the salmon embryo, and if so, what was its 
character. The result of Mr. Mattocks’s work (pub- 
lished in Anat. Anzeiger XIII Bd. Nr. 24), was to show 
that the common anlage does exist in the salmon; that it 
is not a furrow, as in Serranus, but a thickened stripe of 
ectoderm as in selachians; that it divides into three parts, 
the middle becoming the auditory sac, the posterior the 
rudiment of the lateral line, and the anterior remaining 
as a very noticeable thickening situated above the anterior 
gill clefts. It thus turns out, as might have been ex- 
pected, that the peculiarly distinct, furrow-like character 
of the analge in Serranus, is not universal in teleosts. 
The difference in the character of the anlage between 
Serranus and Salmo is perhaps associated with the dif- 
ference in the character of the two eggs. One is small, 
light, the embryo cosisting of comparatively few cells, 
the other large, heavy, the embryo relatively massive and 
of many cells. Without dwelling on this point (which 
like other similar questions can be cleared up only by an 
extensive comparative study of closely related forms, 
aided, where the method is practicable, by intelligently 
put” experiments—in this connection see Davenport’s 
very suggestive ‘‘Catalogue of the processes concerned 
in Ontogeny.’ Bull. Mus. Comp. Zool. Vol. XXVII. 
No. 6), it is safe to say that comparative embryology 
lends some support to the generalization that in embryos 
of the former type invagination or evagination is apt to 
occur, while in embryos of the latter type the invagina- 
tion or evagination is frequently represented by solid in- 
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