and Laboratory Methods. 2299 



peculiar penetrating and irritating action. I recently purchased some cowhage 

 hairs for the purpose of mounting, and as I could only procure them in some- 

 what large lots, I have more than I can use. Should any of your readers wish 

 to examine the hairs I shall be glad to share with them as long as my supply 

 holds out. Of course, the serious consequences that would follow should any of 

 the hairs get into the eyes, must not be forgotten when mounting." 



Techni(,)UE in Study of Body Hairs of Lepidopterous LARv.ii. Am. Nat. 

 xxxvi : 427. — Special histological methods were found necessary to successfully 

 differentiate the exceedingly delicate nerves of touch. For general anatomy of 

 the sense hairs the usual fixing and staining methods were used ; but for stain- 

 ing the peripheral nerve fibers and cells the intra vitam methylen blue method 

 was found especially useful. Griibler's B.x methylen blue, ^ per cent, solution 

 in normal salt, was used. Injection by means of a small syringe was made 

 usually in the side, back of one of last abdominal segments, and enough 

 liquid injected to color the segments, near the head, care being taken 

 to insert the canula only under the hypodermis and muscles and not 

 into the alimentary canal. After injection the insect was left quiet — it must 

 remain alive — for about three hours for most insects, but with some, as with 

 Pieris, two hours was a better time, and four hours seemed best for Datana 

 larvae. After this period the nerves and nerve oells should be well stained and 

 almost all other tissue free from stain. The specimen is then cut open length- 

 wise and pinned out over a hole cut in sheet cork, the muscles and viscera are 

 removed by careful dissection, and then, on examining under a microscope, the 

 nerves and nerve cells are seen stained upon the surface of unstained hypo- 

 dermal layer. By keeping the preparations wet with normal salt solution and 

 using different powers of the microscope, much may be learned regarding 

 the structure and distribution of the peripheral nervous system. The silk worm, 

 Bombyx mori, gave very good results for this work. 



Such preparations fade in an hour or less and the ultimate distribution of 

 the terminal nerve fibers cannot be seen without sectioning. 



The following modification of Bethe's formula for fixation was used : 



Ammonium molybdate Ig. 



Con. HCl. ------------- 10 drops 



Dist. H2O - - 100 c. c. 



This solution was used ice cold and allowed to act on the tissues from eight 

 to twenty-four hours, after which they were washed well in cold distilled water 

 and placed in absolute alcohol for about three hours, then cleared in xylene, and 

 either mounted whole or embedded and sectioned. 



QUESTION BOX. 



No. 30. What is the exact formula for Kyserine fluid ? 



