140 BIOCHEMICAL SYSTEMATICS 



occurs in some algae, fungi, lichens, Gnetaceae, and numerous mono- 

 cot and dicot species. Others, such as volemitol, polygalitol, and 

 styracitol are known in only one or a very few species. 



In spite of their rather broad distribution, mentioned above, 

 within certain delimited taxonomic groups the sugar alcohols may 

 have a meaningful distribution. For example, Plouvier (1948) has 

 shown that galactitol occurs in branches, bark, and leaves of numerous 

 species of the family Celastraceae, while it is absent from the related 

 families, Rutaceae, Simarubaceae, Meliaceae, Rhamnaceae, and 

 Vitaceae. It also occurs in the Lauraceae {Cassytha filiformis), 

 Scrophulariaceae {Melampyrum species), and Hippocrateaceae {Pris- 

 timera indica). The last example is interesting in view of the fact 

 that Bentham and Hooker, and others, have included members of this 

 family in the Celastraceae. 



Among algae galactitol seems to be restricted to the red algae. 

 In contrast, mannitol is often found in brown algae but not, appar- 

 ently, in the reds. Quillet (1957) found mannitol in seventeen species 

 of brown algae, sometimes comprising up to 50 per cent of the dry 

 weight. Volemitol was present in one species, Pelvetia canaliculata. 

 Cmelik and Marowic (1950) found mannitol in Adriatic species of 

 Cystosura, Sargassum, Laminaria, Dictyopteris, Fucus, and Padina 

 with a maximum accumulation at the beginning of winter. However 

 at no season was mannitol obtained from red or green algae. Actually, 

 the authors say that "practically" no mannitol was obtained from 

 red or green algae at any season. It is not clear whether or not 

 small quantities were actually detected in some. Large seasonal 

 variation in mannitol content sometimes occurs. Black (1948) noted 

 over fourfold differences in mannitol content of some Laminaria 

 species in Scotland, with the maximum concentration coming in mid 

 or late summer. In L. cloustonii the dry weight mannitol content in- 

 creased from 18 per cent at one-half fathom to 36 per cent at four 

 fathoms. 



Among flowering plants, mannitol occurs rather widely, among 

 so many families that a significant familial distribution is unlikely. 

 Mannitol is exceptionally common, however, in the family Oleaceae. 



Sorbitol has a more limited distribution among angiosperm 

 families, e.g., the Rosaceae. According to Barker (1955) if detached 

 leaves of certain Rosaceae are kept in the dark to eliminate starch and 

 then floated in a solution of sorbitol, starch is synthesized. The leaves 

 cannot utilize mannitol or galactitol to form starch. Similarly, leaves of 

 Adonis vernalis (Ranunculaceae) and certain species of the Oleaceae 

 will utilize dulcitol and mannitol respectively. It would be interesting 

 to repeat certain of these experiments using methods of modern tissue 



