246 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1907. 
EXPLANATION OF THE FIGURES. 
Fig. 1. Section through pure or almost pure red. Swollen in water 
- and examination with a Zeiss apochromat, 
N. A. 1.40,0 2 mm. focus. Central white light, 
a the limiting zone, 0 first Zenker lamina, c¢ 
second interval, d deeper lying lamin, with 
indefinite edges, e unlaminated zone. 
Fig. 2. Section through the blue, in the 
reproduction the deeper lying lamine are 
badly drawn. Conditions of examination as 
in fies dl. 
Fig. 3. Section through the red in dry— 
that is, in gelatine not swollen in water. 
Examination in Canada balsam. Central 
monochromatic light. 
Fig. 4. Section through greenish yellow. 
Same conditions as in fig. 8. The limiting 
zone and the grains in the individual laminee 
can not be seen. 
Fig. 5. Section through pure brilliant white. 
Swollen gelatine, a opaque mirror zone, 0 the 
fine stripes lying under the mirror zone. 
Fig. 6. Section through yellowish white, a 
mirror zone, ¢ fine stripes, @ lamine corre- 
sponding to the yellow. 
Figs. 7, 8, and 9. The action of intensifica- 
tion on the color. 
Fig. 7 shows the unintensified color, the 
stripes are too dark in the reproduction. 
Fig. 8. The same color intensified once in 
a sublimate bath. . 
Fig. 9. After two intensifications. It will be observed how the 
scarcely visible grain in fig. 
7 becomes thick and dark in 
fig. 9. 
Fig. 10. Red. The thick- 
ness of the first lamine was 
reduced by friction, so that 
blue and green stripes appear. 
Fig. 11. Section through 
bright green, which by over- . 
exposure and _ overdevelop- 
ment has become white; 6 
mirror zone, ¢ fine stripes belong to the white; the other lamine be- 
long to the green. 
Fig. 4. 
weet 2. 
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eB FIST 
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44 
