CAROTINOIDS IN THE CRYPTOGAMS 93 



of the carotinoids which appear to be produced by certain of these 

 organisms. Splendid opportunities for research exist also in regard 

 to the factors governing the kinds and amount of the pigment pro- 

 duced in each case. Such a study offers some fascinating possibilities 

 in connection with the discovery of the true function of the carotinoids 

 in plants. No matter how acceptable the theories appear to be which 

 arc at present in the ascendency regarding this function, it is to be 

 admitted that no theories have been advanced which can claim much 

 experimental basis. It seems logical to assume that much valuable 

 information might be secured if it could be found possible to control 

 the growth and character of carotinoids in simple plants, like the 

 bacteria. If the carotinoids are, after all, merely by-products of plant 

 cell activities we should know this fact. In general, as plant life 

 ascends the scale of complexity carotinoids become an established 

 product of the cell life, and their invariable appearance in the chloro- 

 plastids has been interpreted in favor of a functional theory. The 

 fact that the same pigments appear at times in other organs of the 

 chlorophyllous plants and also in plants which lack chlorophyll en- 

 tirely may, however, be significant. At any rate the possibility is 

 not to be overlooked of throwing some light on this question through 

 a study of the carotinoids in bacteria. 



Carotinoids in the Algae 



The plan which will be followed will be to present the available 

 knowledge regarding each class of algae separately. The species which 

 have been examined will be tabulated, together with the names of the 

 investigators and the dates their work was published. The author 

 has found such an arrangement helpful in the study of the subject 

 and believes it will furnish a convenient mode of reference for future 

 workers in this field. The order of presentation of the various classes 

 follows in general a descending scale with regard to complexity of the 

 plant forms. 



The Phceophyceac. These plants, commonly known as the brown 

 or olive-brown sea-weeds, comprise a large group, which are mostly 

 marine plants. They are found everywhere in the seas, especially in 

 the colder waters. A few of the species are of economic importance. 

 Laminaria saccharina, which contains the carbohydrate mannite, is 

 used in the Orient for food. The carotinoids of this Hass of algae are 

 better known both qualitatively and quantitatively than the chromo- 



