32 HEMOGLOBIN 



it is none other than haemochromogen ; but in what company to 

 meet it ! Sherlock Holmes himself could not make a more dramatic 

 appearance than that of a blood pigment in a mixed company of 

 yeast cells, bacteria and onions. 



If then we can derive a haemochromogen from cytochrome is it 

 possible to derive a cytochrome spectrum from haemochromogen? 

 Seemingly that can be accomplished. At all events a family of 

 characteristic spectra can be obtained by treating various haemo- 

 chromogens with potassium ferricyanide. These spectra differ no 

 more from cytochrome than the cytochrome spectra from various 

 sources differ from one another — as is shown in Fig. 7. The upper- 

 most two spectra are those of the cytochromes of yeast and of 

 guinea-pig's muscle ; the three lower ones are obtained by the alternate 

 treatment, with potassium ferricyanide and a reducer, of nicotine- 

 haemochromogen, pyridine-haemochromogen and globin-haemochro- 

 mogen respectively. 



605 600 595 590 585 580 575 570 565 560 555 550 545 540 535 530 525 520 515 



gl<i Cytochrome in yeast cells sl^ S|C sirf 



_igl . iJ idj ■"■ 



ml C4U ol 



ola Cy tocht-ome tn muscles of Gav,neapi.ggl?) glc 



col m| ml 



I,, Nicotine haemochromoqen 51^ 



treated with K-ferrl-cygnlde &Na2S204 io| 



u Py»"lcLine haemocViromoqen Sl^ 



treated wutK K-fe rri.-cyani,de t^^a;3204 m| 



„ Globln haemochromogen §Ij, 



treated with K-ferri-cyanvde4Na,Sj04m| 



1 1 1 r 1 T ^-T^ 



605 600 595 590 585 580 575 570 565 560 555 550 545 540 535 530 525 520 515 



Fig. 7. 



If, as the foregoing observations seem to suggest, haemochromogen 

 is closely connected with cytochrome the question naturally arises: 

 Is it possible to find either haemochromogen or haematin in cells 

 which subsequently contain cytochrome, but which never contain 

 haemoglobin? The answer is that haematin may be so found, both in 

 cells which will one day contain cytochrome and in cells which 

 actually do contain cytochrome. This is true not only of the animal 

 but of the vegetable kingdom. The whole history may be seen in the 

 blow-fly : 



If one examines spectroscopically the larva of such a fly one sees that the adipose 

 tissue holds a great quantity of haematin and a little ordinary haemochromogen whilst 

 the larval muscles in addition to free haematin contain cytochrome. During the 

 metamorphosis the quantity of free haematin in the adipose tissues gradually diminishes. 



