VISUAL CELLS IN AMBLYSTOMA 497 
The conditions in retinae of forty-eight hours further develop- 
ment are seen in figure 3. The protoplasmic buds have become 
larger and assume a blunt conical shape. The globules occupy 
the proximal portion of the protoplasmic mass, whereas distal to 
them occur masses of deeply staining granules similar to the con- 
ditions shown in figure 2. 
As regards the origin of the clear achromatic globule, Cameron 
claims that it is extruded from the nucleus. He supports his 
contention by observations which both he and Bernard made in 
Fig. 2 Developing visual cells from the retina in an embryo of 11 days after 
the tail-bud stage of development. X 1040. 
Fig. 3. Developing visual cells from the retina of an embryo of 13 days after 
the tail-bud stage. XX 1040. 
which they found a collapsed condition of the nucleus subsequent 
to the supposed ‘sudden’ discharge of its achromatic material. 
This view is contradicted by Leplat (713). Graham Kerr (’19) 
states that the ‘fatty’ globule, which stains black with osmic 
acid, has its origin in the protoplasmic bud from the primitive 
visual cells. 
Cameron attributes to this clear globule the power of ingest- 
ing pigment from the hexagonal pigment cells, and the intensely 
stained granules which he found on the summit of this globule 
(figs. 2 and 3) he claims to be the pigment ingested from the pig- 
