METHODS OF INVESTIGATION. 63 
Hoppe-Seyler * quotes the following figures for the composition 
of epidermis and some of the tissues derived from it: 
seyigm® | nas. | ama | prot | este 
Carbon .........06. 50.28 50.65 51.00 51.03 | 51.41 
Hydrogen.......... 6.76 6.36 6.94 6.80 6.96 
Nitrogen........... 17.21 17.14 17.51 16.24 | 17.46 
Oxygen....esseeee- 25.01 20.85 21.75 22.51 19.49 
Sulphur............ 0.74 5.00 2.80 3.42 4.23 
100.00 100.00 100.00 100.00 | 99.55 (?) 
Hlenneberg + obtained the following figures for the composition of 
two samples of pure and dry wool, calculated ash-free: 
I. II. 
CarbGticsciesaxieeGot ei enh 49.67 49.89 
Hydrogen ...... 0... cece eee eens 7.26 7.36: 
Nitrogen............... Secu sins 16.01 16.08 
Oxygen..........08. jee date metas 23.65 23.10 
Sulphur’ cicec..eseceeeees ree 3.41 3.57 
100.00 100.00 
The following analyses by Rubner,{ Stohmann & Langbein,§ 
and Argutinsky|| show the ultimate composition of ash-free muscular 
tissue after prolonged extraction with ether: 4 
or of 
Hydro- |nitrogen,| Sulphur, | Oxygen, | pictio 
Per Cont. jp BoB, 4, [ber Cont,|Per Cent, [Per Cont. prea, 
Rubner.........---+-+- 53.40 16.30 5.6561 
Stohmann and Langbein.| 52.02 | 7.30 | 16.36 24.32 5.6409: 
Argutinsky.......-+---- 52.33 7.30 | 16.15 24.22 
* Physiol. Chem., p. 90. + Neue Beitriige, etc., p. 98. 
¢ Zeit. f. Biol., 21, 310. § Jour. f. prakt. Chem., N. F., 44, 364. 
|| Arch. ges. Physiol., 55, 345. 
qIt has since been shown by Dornmeyer (Arch. ges. Physiol., 65, 90) 
that such material is not fat-free. 
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