28 



HEMOGLOBIN 



Arachnids. Epeira diademata. 



Insects. About forty species have been examined, all of which contain 



cytochrome, among which are the house-fly, the lesser house-fly, 

 the blow-fly, the tsetse-fly, Oastrophilus inteslinalis, Eristalis 

 tenax. Anopheles maculipennis, Culex pipiens, the hornet, wasp, 

 bumble-bee, honey-bee, silkworm moth, wax moth, etc. 



Vertebrates. Cytochrome was found in the tissues of fish, frog, pigeon, guinea- 

 pig, rabbit and sheep. 



Perhaps the most exciting excursion of Keilin's work is that which 

 took him into the vegetable kingdom. For the cytochrome spectrum 

 may be found in a great number of plants ranging from the lowest 

 to the highest forms. It may be seen in yeast, equally it may be 

 seen in the onion and in certain aerobic bacteria. Thus it is to be 

 found in the animal kingdom right down through every phylum to 

 the worms, and in the vegetable kingdom from the bacterium right 

 up to the flowering plant — surely a sufficiently universal distribution. 



Fig. 5 gives the position of the cytochrome bands in a number 

 of typical forms. 



610 605 600 595 590 585 580 575 570 565 560 555 550 545 540 535 530 525 520 



a BacLLLus subtllis 



^Id 



" Yeast ceLls 



a Eschalot , bulb 



" Bee , thoracic muscles 



SJ" Dytiscus " 



Gallf 



" Snail, radula »» 



■"!/< 



« Frog , heart 



" Guinea-pig, heart muscle § 



610 605 600 595 590 585 580 575 570 565 560 555 550 545 540 535 530 525 520 



Fig. 5. Spectra of cytochrome from various sources in the animal and vegetable 



kingdoms. 



An inspection of Fig. 5 will show why I had some misgivings 

 about saying that cytochrome was identical in all forms of life. 

 A detailed analysis shows that going from form to form the whole 

 spectrum is now a few Angstrom units to the right, now a few to the 

 left, the largest divergence being in band 6, that between eschalot and 

 bee, and amounting to 26 a.u. 



