1 1-' CHEMICAL DIFFERENCES 



BETWEEN SPECIES. 



54. Haemoglobin crystals. Note the different shapes of crystals from different 

 species of animals. 



55. Pricipitins. Four small test-tubes are half- filled with : 



(1) Ox serum ; 



(2) Horse serum ; 



(3) Ox serum ; 



(4) Horse serum. 



To (1) and (2) is added serum from a rabbit which has been previously inoculated 

 with ox serum and to (3) and (4) serum from a rabbit which has been inoculated with 

 horse serum. Observe the effects of these additions. 



