GENERAL METABOLISM 



[PT, III 



Brubacher), for the guinea-pig (Inaba), for the rabbit (Fehling), the 

 mouse (von Bezold and Inaba), and the cow (Moulton, Trowbridge 

 & Haigh). Moreover, the process is continued after birth, as the 

 complete figures of Hatai for the rat, and of Thomas and of Weigert 

 for the cat and dog clearly show. On the basis of these facts, several 

 authors have concluded that a decreasing water-content is a uni- 

 versal accompaniment of growth, and the more rapidly the latter 

 takes place the more rapidly does the drying up of the tissues go on. 

 Cramer found that the water- 

 content of neoplasms was 

 always higher by at least 5 

 per cent, than that of normal 

 tissues, and that it varied 

 directly with the growth-rate 

 of the particular neoplasms, 

 i.e. those growing the fastest 

 as measured by mitotic index 

 had the most water (see 

 Fig. 229). Cramer concluded | 

 that a high water-content | 

 was intimately associated a 

 with a high growth-rate. ■- 

 Then Ruzicka later was | 

 much impressed by these 

 facts, and enunciated a "law 

 of protoplasmic hysteresis", 

 while Rocasolano and Le- 



292 J 63 T 2/ 12 



Tumours 



Chick 

 Embryo 



Normal 

 Fig. 229. 

 292, J, 63, T, 27 & 72 are strains and a and b 

 generations of strains. 



Breton & Schaeffer pointed out its relations with the paraplasmatisa- 

 tion of the tissues with age (see p. 747). Ruzicka regarded the ageing 

 process as a continual tending of protoplasm towards stability, solidity, 

 insolubility and dryness. Some curious digestion experiments which 

 he made are relevant here. The time required to dissolve embryonic 

 tissues by trypsin under standard conditions he found to vary as 



follows : Hours 



Frog. Blastulae ... ... ... ... 3-6 



Embryos with tail buds ... ... 26-32 



Embryos with external gills ... 43-53 



Tadpoles 19 mm. long ... ... 71-80 



In all cases there was an insoluble residue which increased in amount 

 per gram of original material with age. Ruzicka also showed that the 



