BIOCHEMICAL ARCHITECTURE 3 



of their body weight during 5 hours immersion in water (Wolf, 

 1940). In the often very dry soils of the tropics it is possible that 

 the normal dehydration of earthworms proceeds even further. 



It is evident from the foregoing that water is able to cross the 

 boundary formed by the skin with comparative ease. The ability 

 to survive although the water content of the body shows consider- 

 able and rapid fluctuations is evidently of great value, but little 

 work has yet been directed towards an elucidation of the mecha- 

 nisms by which bodily functions are maintained under conditions 

 of water stress, either ingoing or outgoing. 



Earthworms show great tolerance towards water loss, and can 

 recover from drastic dehydration. If water is lost rapidly a deficit of 

 43-50% body weight in 5-9 hours can be withstood; Jackson 

 (1926), and Schmidt (1927) kept earthworms alive after they had 

 lost 30% body weight in 5| hours. A more protracted drying 

 period, as used by Roots (1956), of 20-24 hours can lead to a 

 greater loss of up to 57-59-7% of body weight and the animals, 

 Liunbricus terrestris, still remain alive. Under the same conditions 

 a smaller species, A. chlorotica, loses 50% of its body weight in 3 

 hours. A loss of 60% of body weight, corresponding to 70% of the 

 total water content of L. terrestris, and 75% of total water of A. 

 chloroticay can be tolerated. The ability of earthworms to withstand 

 such great losses of water is of aid in maintaining field populations 

 under exceptionally arid conditions (Zicsi, 1958). 



Chemical Composition of the Body 



Whole Body 



The average dry weight of earthworms is about 15-20% of the 

 fresh weight. This represents the entire carcass weight after 

 complete dehydration. The chemical constitution, protein, amino- 

 acids, carbohydrates, etc., of the carcass has been investigated for 

 only a few oligochaete species. 



Protein accounts for the largest fraction of the dry weight. 

 It has been estimated variously (see Table 1) at between 53-5% 

 and 71-5% of the total dry weight of Lumbricus terrestris. This 

 indicates a wide variation in the body proteins, and this variation is 

 also shown by analysis of other types of biochemical compounds. 

 For example Durchon and Lafon (1951) found a lipid content 



