Miy-Juiif i-iSj.l 



psrcjiE. 



17 



Lieing' so hi'ittle th;it fuw can lit' renioveil 

 without breaking. My experiments 

 were all m:ide with scales from a speci- 

 men dried at least over ten years ; pos- 

 sibly a fresh specimen WMukl have less 

 brittle scales. 



Further microscopic examination of 

 narrow scales and huiis reveals a longi- 

 tudinal striation, the striae of which are 

 from 0.0015 '^° 0.0020 mm. (or even 

 further) apart. This striation, which 

 for greater distinctness I will call the 

 "coarser striation,'" is present on hairs, 

 less marked on elongated scales, and 

 not generally observable on broad scales 

 (such as represented in fig. 11,/'). This 

 coarse striation is visible after the color 

 has been removed from the scales and 

 hairs by reagents. It is easily seen to 

 be external on the cylindric.d hairs, 

 extending beyond the colored portion of 

 the hairs. 



Still higher magnifying power brings to 

 view a second striation, which I will call 

 the "finer striation." This striation was 

 much more difficult to see than the coarser 

 striation, the striae being very delicate 

 and onlv o.oooS to 0.0009 mm. apart. 

 Unlike the coarser striation, the finer 

 striation is more evident on broad scales 

 and least evident or not discernilile, at 

 least with the objectives at m\- com- 

 mand, on narrow scales and oii hairs. 

 The finer striation is further unlike the 

 coarser striation in following no definite 

 direction on the scale, sometimes being 

 in one direction in one portion of a scale 

 and in another direction in another part 

 of the same scale. In any single com- 

 partment of a scale the direction of the 

 finer striation is approximately the same. 



sometimes a little curved, resembling, 

 as seen under the microscope, the fur- 

 rows of the finger-tips. In adjacent 

 compartments of a scale the finer striae 

 are sometimes at right angles to each 

 other, though oftener in the same direc- 

 tion. I have attempted to represent, 

 on fig. II, (/ and c, the finer striation 

 upon two scales, but the striae, although 

 proportionatelv about the right dis- 

 tance apart, are themselves relatively- 

 coarser than in nature. The finer stria- 

 tion may be at right or at oblique angles 

 (probably also parallel) to tiie coarser 

 striation. The finer striation is most 

 evident in blue or purplish [jarts of 

 scales, altho it exists in other parts ; 

 probably the darker background makes 

 it more plainly visible on blue portions. 

 The finer striae appear to be formed of 

 rows of dots, but my objectives failed to 

 determine this with certainty. The 

 finer striation is invisible on scales 

 treated with liquid reagents to remove 

 the air. 



Both finer and coarser striation are 

 found on the under as well as the upper 

 sitle of the scales. At tlie edges of the 

 scales the coarser striation curves and 

 appears upon the transparent border of 

 the scales, the finer striation (see fig. 

 II, e) curves to meet the margins of 

 compartments ; the coarser striation is 

 evidently an external, longitudinal plica- 

 tion of the scale-membrane, limited in 

 extent by the size of the scale itself, the 

 finer striation is a plication or figuration 

 of the inner side of the scale-membrane, 

 limited in extent by the outline of the 

 compartment to which it belongs. 

 ( "To be continued. ) 



