158 RESEARCHES ON FUNGI 



throughout the gelatinous mass ; and more and more water is 

 absorbed until equilibrium of water-content has been established 

 throughout the fruit-body and the limit of imbibition has been 

 reached. During the absorption of water the jelly increases 

 enormously in volume, loses its horniness, and becomes more 

 and more watery in consistence. The jelly constitutes not only 

 a water-absorbing system but also a water reservoir. After dry 

 weather sets in, it supplies water to the living cells of the flesh 

 and hymenium, and keeps them turgid so that, for some time 

 after the fruit-body as a whole has begun to contract as a result 

 of transpiration, the production and liberation of spores can be 

 continued. 



From the above discussion I think we are justified in believing 

 that the development of jelly in the fruit-bodies of Tremellineae 

 is an adaptation to a lignicolous habit of existence, and that the 

 jelly enables the fruit-bodies which possess it to absorb and store 

 water rapidly when rain comes after drought. 



Among Algae, the thalli of the Fucaceae especially their 

 terminal fruiting branches have a very similar structure to the 

 fruit-bodies of the Tremellineae ; for, in the main, they consist of 

 branching and anastomosing, hypha-like cells connected together 

 by, and embedded in, a transparent gelatinous matrix formed 

 from the outer, swollen, confluent layers of the cell-walls. The 

 thalli of the Fucaceae grow upon rocks and, as is well known, are 

 exposed to the air at low tide. Whilst so exposed, particularly in 

 warm sunny weather, the thalli transpire and contract consider- 

 ably ; but, when the tide rises and the sea-water envelops them 

 again, they rapidly absorb water by imbibition and re-expand. 

 Here, just as in the Tremellineae, where vitality must be retained 

 during the persistence of dry conditions, a gelatinous matrix has 

 been developed which functions by absorbing and storing water 

 rapidly as soon as free water again becomes accessible. 



The gelatinous matrix of the fruit-bodies of the Tremellineae, 

 when fully expanded, forms by far the larger part of the fruit- 

 body substance, and the living anastomosing hyphae which it 

 envelops, excepting at and near the hymenium, are relatively few 

 and widely separated. Now the jelly in an expanded fruit-body 



