782 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



[Vol. 2 



Kylin ('14) and others have also demonstrated pectin-like 

 compounds forming the middle lamella in various members of 

 the Fucaceae. These exist as the calcium salts of pectic-like 

 acids which Kylin designates "Fucinsaure" and "Algin- 



• • 



saure. " 



PHYSIOLOGICAL SIGNIFICANCE OF ALGAL SLIME 



It is seen that algal slime is made up chiefly of the an- 

 hydrides of hexoses and pentoses — carbohydrates that must 

 be broken down to simpler form before assimilation by the 

 plant would be possible. Two questions naturally arise : (1) 

 Do the algae concerned form enzymes that will hydrolyse these 

 highly condensed carbohydrates to assimilable form? (2) 

 Does the slime itself arise through the breaking down of the 

 hemicelluloses of the cell wall through enzymic or other 

 causes, or does it represent a final stage in the condensation 

 of those hemicelluloses ? 



Algal slime as a reserve product. — Galactanases and man- 

 nases have been demonstrated in the phanerogams and in the 

 fungi by Bourquelot and Herissey ('99), Griiss ('02), and 

 Herissey ( '03). The last worker especially has clearly shown 



t as re- 



the distinct role that galactans and mannans may plaj 

 serve products in the tubers of the Orchidaceae and in many 

 of the Leguminoseae. It is significant that Gran ('02 a ) was 

 able to isolate a marine bacillus, B. gelations, that acted on 

 part of the constituents of agar-agar to give a reducing sugar. 

 From the standpoint of a possible symbiosis it would be in- 

 teresting to know if this organism has the ability to fix free 

 nitrogen. Saiki ('06) experimented with a number of algal 

 and lichen preparations containing a large proportion of 

 carbohydrates as galactans and pentosans, and concluded that 

 the latter could not be transformed into sugars readily by 

 carbohydrate digesting enzymes of animal origin and scarcely 

 more so by the vegetable enzymes, either of the higher plants 

 or of bacteria. 



Still less is known of the digestion of pentosans by the 

 higher plants. Schone and Tollens ('92) found no decrease 

 in the amount of pentosans during germination and conclude 



