CHAPTER I 



INTRODUCTION 



IT is commonly recognized that what is known 

 as chlorophyll is an essential constituent of 

 healthy plant life, and its absence, or presence 

 in insufficient quantity, is the cause of chlorosis, 

 which is one of the most formidable diseases 

 to which plants are liable. This chlorotic con- 

 dition is due to an absence of iron, as without 

 iron chlorophyll cannot be formed (see Ency- 

 clopaedia Britannica, vol. xix., p. 52), and is 

 often successfully treated by washing with a 

 weak solution of sulphate of iron. Now what 

 chlorophyll is to the plant, haemoglobin is to 

 the animal, the one being a red modification of 

 the other, as I shall show in a later chapter, 

 and Macallum holds (see Colour in Nature, by 

 Marion J. Newbigin, D.Sc.) that chlorosis 

 in plants and animals is due to the same cause, 

 a deficiency of iron. It follows from this that 

 herbivorous animals eating chlorotic food, 



B 



