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SCIENCE. 



[N. S. Vol. XIX. No. 473. 



passed unchanged througli the intestine 

 and into the body tissues much as had been 

 the ease in the experiments with the pre- 

 ceding. 



Graff later reached very similar conclu- 

 sions concerning coloration in the leeches, 

 but was able to go a step farther than Bisig 

 had done and to show in great detail the 

 exact process througli which it was 

 brought about. He found in the endothe- 

 lium certain migratory cells which wander 

 about in the coelom or penetrate through 

 the tissues, and that among their func- 

 tions one of the most important seems to 

 be the absorption of foreign bodies and 

 their conveyance into the mouths of the 

 nephridia or through the tissues to the 

 hypodermis and their lodgment in that 

 tissue. He was even able to show that the 

 special markings or color patterns which 

 are so characteristic of the animals may 

 be explained by the disposition of the mus- 

 cle bands, and their relation to the lines of 

 pigmentary deposition by the wandering 

 cells, which Graff has designated 'excreto- 

 phores.' He was also able to confirm the 

 results of Eisig as to the experimental 

 demonstration of feeding Avith various pig- 

 mentary matters, and subsequently tracing 

 them from point to point in the process of 

 elimination. Furthermore, he showed that 

 the amount and density of pigmentation 

 Avas closely related to the intensity of me- 

 tabolism, being greatest in those specimens 

 which were most voracious feeders. 



Observations of a similar character have 

 been made upon certain of the protozoa, 

 particularly upon Stentor. Schuberg in 

 1890 found that the blue-green pigment 

 so characteristic of this organism was con- 

 stantly being excreted bodily in the form 

 of definite graniiles. 



In 1893 Johnson, in an extended study 

 of the morphology of these protozoa, con- 

 firmed the preceding observations, and 

 showed that the pigment was excreted 



along with other excrementitious matter. 

 He found also that the principal region of 

 excretory activity Avas at the base of the 

 animal, Avhere Avas formed after a short 

 time a definite mass of debris near the foot. 



Perhaps one of the most important con- 

 tributions along this line is that of Har- 

 mer on the character of the 'brown body' 

 of the polyzoa. By a series of critical ob- 

 servations upon the life-history of these in- 

 teresting organisms and painstaking exper- 

 iments in feeding with carmine and other 

 pigments, he was able to prove beyond 

 reasonable doubt that the so-called 'broAA'n 

 body' of the polyzoa is a direct product 

 of the destructive metabolism Avithin the 

 body and its excretion in a mass at this 

 particular region. He found that the leu- 

 cocytes of the funiciilar organ as well as 

 certain cells of the organ itself engulfed 

 pigmentary wastes, and with the periodic 

 decline of the polypides these cells be- 

 came crowded into a close mass, thereby 

 constituting the 'broAvn body.' The neAv 

 polypide arising by a sort of regenerative 

 process was found to be ahvays devoid of 

 any coloration, no pigment appearing for 

 some time following the activity of the 

 ncAV polypide, but that it is formed in reg- 

 ularly increasing amounts Avith the age 

 and degree of metabolism of the organisms. 



Correlated Avith these views concerning 

 the origin of certain colors and their dis- 

 position in the organism is that of the rela- 

 tion of coloration to the food. It has long 

 been known that in many cases there is a 

 more or less intimate relation of color to 

 the food consumed by certain animals. 

 Instances of this are too numerous for de- 

 tailed consideration here. Let it suffice 

 that DarAvin, Semper, Eimer, Koch, Bed- 

 dard, Poulton, Gunther and many others 

 have, by extended observations and by de- 

 tailed experimentation, apparently estab- 

 lished the general fact. ' Beddard quotes 

 the following observation made by G. 



