THE BIO-CHEMISTRY OF ANIMALS AND PLANTS 123 



urobilin, the iron-free pigment found in bile and urine after 

 haemorrhage, giving all the characteristic reactions and the 

 spectrum of the natural substance. On subcutaneous injection 

 of haemopyrrol, urobilin could be easily demonstrated in the 

 urine. 



In the beginning of last year Marchlewski brought forward a 

 further most interesting proof of the near relationship between 

 the two pigments. A few years ago Zaleski succeeded in 

 reconstituting haemin by introducing iron into hasmatoporphyrin 

 (or rather into the more active mesoporphyrin). The artificial 

 haemin possessed the same crystalline form (Teichmann's 

 crystals), and practically the same spectrum as ordinary haemin. 

 At about the same time Laidlaw, in Cambridge, published 

 similar results, and he succeeded in preparing artificially the 

 brilliant red pigment Turacin, contained in the wings of certain 

 birds, by combining copper with haematoporphyrin. Working 

 on the same basis, Marchlewski was able to introduce iron into 

 phylloporphyrin, and thus obtained a Phyllohcemin, which 

 gave the same spectrum as haemin. This is the first instance 

 of the transformation 'of a chlorophyll derivative into one of 

 haemoglobin. 



This last and perhaps most striking proof of the near relation- 

 ship of vegetable and animal life brings to an appropriate 

 conclusion my endeavour to present some of the problems of 

 bio-chemistry, in which both forms of organic nature have a 

 share. A comparative study of the chemical biology of plants 

 and animals deserves more attention than it has hitherto re- 

 ceived. It not only brings home to us the resemblances, but at 

 the same time helps us to arrive at a clearer understanding of 

 the fundamental biological differences between the members 

 of the two forms of life. 



In view of the absolute dependence of animal on plant life, 

 considerations of this nature may not only prove to be of 

 scientific interest, but also of economic importance. 



