t'AROTINOIDS IN THE CRYPTOGAMS 123 



piirment, possibly fucoxanthin, predominates among the chromolipoidfl 

 pre-ent. Brownish-red and yellow water-soluble non-carotinoids are 

 the chief cause of the color of these plants. 



Carotinoids are unquestionably present in the flagellates, although 

 their exact nature remains to be determined. The red pigment which 

 characterizes the so-called eye-spots of Euglena species does not ap- 

 pear to be identical with any of the known carotinoids, but resembles 

 the red carotinins, the determination of whose relation to the carotin- 

 oids is greatly to be desired. 



Carotinoids are normal constituents of the blue-green algae. The 

 facts which are known point to the presence of carotin and fucoxanthin 

 in these plants. Another pigment is present in certain species, which 

 is non-carotinoid in nature but which resembles carotin in having a 

 yellow color in alcohol and a red color in carbon disulfide. Its exact 

 nature is not known. 



Carotinoid colors are more common among the fungi than among 

 the algae but the color in many cases appears to be due to other 

 pigments. In fact, many fungi seem to be entirely devoid of carotin- 

 oid pigments. 



Among the Basidiomycetes, a few species in the mushroom family 

 apparently owe their color to carotinoids. The striking examples of 

 carotinoid pigmentation, however, are the rusts, whose yellow and 

 red colors are due to carotin or a very closely related pigment. It 

 is not known whether other carotinoids are involved. 



Several of the brilliantly colored cup fungi owe their color to 

 carotinoids. The exact nature of these has not been determined in 

 the case of the Discomycetes, but in the case of certain Pyrenomycetes 

 carotin is undoubtedly concerned, as well as red carotinoid-like pig- 

 ments which require further study. 



Carotinoids have been identified in a few molds and yeasts but 

 their nature is unknown. 



There is considerable uncertainty regarding the exact relation to 

 the carotinoids of certain yellow pigments characterizing the slime 

 molds, but xanthophyll or carotin-like pigments are indicated in the 

 case of certain species. 



Carotinoids are formed by several species of bacteria. Carotin 

 appears to be the principal pigment concerned in the case of B. 

 egregium and Spacrotilus roseus. The exact nature of the pigment 

 has not been determined in the case of the other species in which 

 carotinoid? have been determined to be present. 



