ENDOGENOUS PORPHYRIN METABOLISM 585 



pliyrin. The last-named authors termed the phenomenon "chromodacry- 

 orrhoea," the flow of colored tears. The phenomenon could be caused by 

 feeding rats a diet lacking in vitamin B factors. The mi.ssing factor was 

 later found to be pantothenic acid by Figge and Salomon {75J^) and Smith 

 {2581). Since Ellinger and co-workers {OGJf) had observed, several years 

 before the investigation of Chick, that coproporphyrin excretion in the rat 

 was increased in the urine of rats deprived of B vitamins, chromodacry- 

 orrhoea appeared to be further evidence of an increase of porpliyrin forma- 

 tion. Figge and Salomon showed, however, that pantothenic acid affects 

 the gland locally {cf. also Smith). The direct effect of the vitamin lack is 

 on water metabolism, and the phenomenon can also be caused by with- 

 holding water. The excretion of the gland, which normally finds its way via 

 the nasolacrimal duct into the alimentary canal, becomes gluey, remains 

 around the eyes and nose, and is smeared over the face in the efforts of the 

 animal to clean itself. 



A difficult problem is raised by the observation of JMcElroy and co- 

 workers {1807) that tlie porphyrin in chromodacryorrhoea is predomi- 

 nantly coproporphyrin, not protoporphyrin, as Chick and co-workers had 

 assumed. This appears to be neither in harmony with the interpretation of 

 the action of pantothenic acid given by Figge and Salomon, nor with the 

 claim of Thomas that the porphyrin metabolism of the gland is not affected 

 by an increase of coproporphyrin formation in the animal. If the proto- 

 porphyrin of the gland is normally excreted in the feces, it should be found 

 in the red smear of chromodacryorrhoea, when the normal way is blocked; 

 if the blocking of this way leads to an accumulation of coproporphyrin in the 

 smear, this porphyrin must be either formed in the gland or accumulated 

 from the general circulation, and should normally pass into the excreta. 



Protoporphyrin is also found in the placenta of rats and mice in the 

 later part of the period of gestation (Thomas, 2798). 



The occurrence of protoporphyrin in the shells of bird eggs has been men- 

 tioned in Chapter III, Section \.i. Little is yet known about the formation 

 of the porphyrin in the mother bird and the way it is deposited in the egg 

 shells. Giersberg (9.97) found that the porphyrin is conveyed in wandering 

 cells which penetrate the uterine epithelium in the final stages of calcification 

 of the shell. Derrien and Turchini {560,561,2835) observed red fluorescence in 

 the uterus of the laying hen and porphyrin granules in the uterine epithelium; 

 these were not found, however, by Richardson {22Jf6). According to van den 

 Bergh and Grotepass {228) glands of the uterus excrete the porphyrin 

 together with calcium albuminate. Po.ssibly the mode of deposition of pro- 

 toporphyrin in hen eggs, in which the whole of the shell is impregnated 

 with a small amount of porphyrin, differs from that in other bird eggs, in 

 which blotches of a porphyrin protein compound are found only on the sur- 

 face of the shell. In bird feathers coproporphyrin III has been found 

 {2898). 



Other isolated observations on the occurrence of porphyrins in nature 

 have been discussed in Chapter III; nothing is known about their physio- 

 logical significance. The formation of porphyrins by microorganisms will be 

 discussed below (Section 3.3.5.). 



