SECT, i] PHYSICO-CHEMICAL SYSTEM 343 



the nitrogen in eggs. 



Gm. % dry weight (ash free) 



^ A . ^ 



% of the total nitrogen Egg- 



, — ^ ■ — \ Pro- mem- Free 



Free tain Pro- brane Nitro- bases and 



Protein Ker- Albu- Ichthu- amino- (N x tein (by pro- Albu- Ichthu- gen amino- Investigate 



total atin men Hn acids 625) diflF.) tein men Hn (direct) acids Fat Ash and date 



66-9 121 548 331 85-37 92-37 1119 50-64 13-65 30-54 7-64 — Konig & Gr 



(1913) 



70-96 11-35 721 52-4 2904 82-75 95-93 10-90 6-92 50-25 13-08 27-87 407 — „ 



85-20 15-7 0-49 790 1485 80-56 89-25 5-10 0-44 70-48 12-89 13-24 IO-7S — 



86-15 12-70 9-15 543 13-9 89-52 85-75 10-88 16-43 46-53 14-33 "-Qi 14-25 — 



68-41 10-50 i-oi 469 315 8933 94-84 9-97 10-48 44-51 14-29 29-88 5-55 — „ 



(loo-o?) — 11-70 880 — 87-80 — — 10-30 77-5 — — 4-50 7-50 Kensington ( 



(loo-o?) 2-7 973 — __ — — — — — — — Hugounenq 



62-0 — — — 379 — _ — — — — — — — Russo (1926) 



94-0 — 27-4 8-05 6-04* — — — — — — — — — Monzini(i9: 



Pigorini (ic 

 96-0 — — — 3-98 65-25 — — — — — — — — Russo (1922) 



(loo-o?) 66-0 3-74 30-2 — — — — — — — — — — Galimard (19 



66-0 — — — 33-0 68-09 — — — — — — — — Levene (i89( 



_ ___ — _________ Nelson & Gi 



(1921) 

 96-4 406 49-8 42-5 366 — — — — — — — — — — 



Q8-5 — — — 1-5 — — — — — — — — — Tomita (1921 



chorionin in addition. 



As is well known, these fishes have a special relation to this sub- 

 stance. In 1858 Stadeler & Frerichs isolated "kolossale Quantitaten 

 von Harnstoff" from the organs of plagiostomes, obtaining a solid 

 mass of urea nitrate when they added nitric acid to their final con- 

 centrates. One liver of an adult Scy Ilium canicula gave them 2 oz. of 

 urea, and similar high figures were reported for Acanthias vulgaris. 

 Teleostean fishes, however, and the cyclostome, Petromyzon planeri, 

 yielded practically no urea, at any rate not more than would be 

 present in mammalian tissues. Stadeler confirmed the selachian 

 results on Raia batis and clavata and on Torpedo marmorata and ocellata. 

 In 1 86 1 Schulze repeated and confirmed Stadeler's work on Torpedo, 

 and in 1888 Krukenberg published an extensive work on the subject, 

 in which he related his unsuccessful attempts to demonstrate urea 

 in the bodies of teleosts {Lophius piscatorius. Conger vulgaris, Acipenser 

 sturio), a cyclostome [Petromyzon fluviatilis and Ammocoetes) and a 

 cephalochordate (Amphioxus lanceolatus) , although he found large 

 amounts of it in the bodies of elasmobranch fishes [Scyllium stellare, 

 Mustelus vulgaris and laevis, Acanthias vulgaris, Squatina angelus, Torpedo 

 marmorata, Myliobatis aquila) and in the holocephalic Chimaera 



