IK) 



2. P!a}if Juiii's. A laruo list of freezing- points of ex- 

 trncled ]tlaiit juices is yiven ])y Dixon and Atkins (1910), 

 ill a table i('i)r()(liu'e(i in Tahiifac Hiolof/icae (7, 4.')l-434, 

 1925). The rrcc/.iiiii' i)()iii1s vary IVoni - 0.:i57° to -2.455°. 



Harris, (Jortner, liofman and Valentine (1921) mention 

 the exceptional ease of a plant, Atrlplcr nuttaUii, which 

 was collected near tiie (Jreat Salt Lake and which had a 

 freezing jjoint of - 14.4°. The same authors obtained 

 excei)tioiuilly high fi-eezing points in cactuses. 



According to Harris, (Jortner and Lawrence (1917), the 

 freezing point is higher in juices exli-acted from leaves 

 near the ground than in leaves taken higher up. The 

 higher osmotic pressure at higher levels is thought to play 

 a role in the ascent of sap. 



3. Blood and Bodji Fluids. Collip (1920a) measured 

 the freezing point of the blood of animals belonging to 

 various orders. He found values varying in mammals 

 from - 0.48° to - 0.70°, in birds from - 0.55° to - 0.69°, in 

 reptiles from -0.46° to -0.70°, in amphibia from -0.44° 

 to -0.76°, in fresh water fishes from - 0.45° to -0.69°. 



The blood cells, in Collip 's experiments, froze, on an 

 average, at a temperature 0.043 degree higher than the 

 serum. 



According to various authors (quoted by ^McClendon and 

 Medes, "Physical Chemistry in Biology and Medicine," 

 Philadelphia, 1925, p. 300), the fluids of the mammalian 

 body have, in general, a freezing point very near that of 

 the whole blood. Such is the case for milk, gastric juice, 

 pancreatic juice, bile, intestinal juice, cerebrospinal and 

 spermatic fluid. Saliva, and sweat were often found to 

 have a higher freezing point, reaching about - 0.1°. Urine 

 had a much lower value, sometimes as low as -2.6°. 



Individual Differences. Some authors have 

 thought that the freezing points of body fluids or of tissues 

 might be specific characteristics of some animal (or plant) 

 grouiJ. Atkins (1909a) attempted to study the individual 

 differences in the freezing point of the blood of birds 

 within the same species. He found — quoting only the 



