1902 - 3 .] Mr John Cameron on the Pineal Body. 
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recess. The latter, on the other hand, shows progressive develop- 
ment after the end of the bilobed condition ; and the tendency of 
this, as a rule, is to cause the opening of the epiphysis to become 
placed to the left of the mesial plane (as has been already pointed 
out in the case of the frog). Although this latter appearance is 
to he found in most of the cases, still, in a few instances, the 
opening tends to remain more or less mesial in position — as will 
he noticed on consulting the accompanying list of specimens which 
were examined. 
Fig. 5 is taken from a toad-tadpole (10 mm. long ; twenty days 
after fertilisation), and shows the epiphysial opening situated to 
the left of the mesial plane ; hut the figure does not represent the 
amesial condition so markedly as the section from which it was drawn. 
Fig. 2 also suggests the blending of the right and left primary 
outgrowths, for the evagination, although now placed distinctly to 
the left side, still shows the presence of two smaller recesses which 
may represent the primary hilohed condition. The nuclei in the 
region of the epiphysial anlage of the frog and newt are found to 
show no difference in their staining reaction with the iron-alum- 
hsematoxylin stain from the adjoining nuclei, such as has just heen 
seen in the case of the toad. 
The newt-embryos were not chosen at a sufficiently early period 
of development to show right and left epiphysial recesses, hut, 
judging from the subsequent stages, the primary hilohed condition 
also probably exists in the case of the newt, for fig. 6 is taken from 
a newt-embryo (5 ’5 mm. long), and is approximately at about the 
same stage as figs. 2 and 4. An examination of this figure will 
demonstrate the fact that the epiphysial evagination lies markedly 
to the left of the mesial plane ; and there is no trace of a right 
evagination. Note that the epiphysial outgrowth shows no lining 
layer of pigment at this stage in the newt. 
The other specimens of newt-tadpoles which were examined 
showed the pineal evagination as arising in the younger specimens 
usually to the left of the mesial plane. Fig. 7 is from an 1 1 mm. 
newt-tadpole, and shows the communication between the epiphysis 
and the thalamencephalon situated to the left of the mesial plane. 
During the later tadpole-stages in the frog, toad, and newt the 
roof of the thalamencephalon becomes more and more thinned out, 
