100 



Mycologia 



relation of fresh weight to dry weight to vary from 1.14 to 1 

 in Parmelia acetabulum to 1.21 to 1 in Teloschistes parietinus. 

 He thinks that respiration and assimilation in lichens are reduced 

 to almost nil in dry times. He found that Cladonia rangiferina 

 and some other higher lichens can endure the dry condition for 

 three months, and, upon the return of moist conditions, the 

 life energies gradually return to their normal condition. Jumelle 

 also experimented with lichens collected at times when they 

 should be near their maximum regarding water content in their 

 natural habitats, and got no very striking increase in the amount 

 of water present in their thalli, the figures for Parmelia aceta- 

 bulum at two different times being 2.07 to 1 and 1.38 to I. He 

 also dipped lichens into water several times, wiped them care- 

 fully and weighed them at once and also after drying. He 

 found that the relation between the saturated weight and the 

 dry weight is for Parmelia acetabulum 3.36 to 1, a proportion 

 above the average for nineteen lichens experimented upon by him. 



Jumelle has also experimented in similar fashion with seed- 

 plants and has found that the proportion between fresh and 

 dry weight varies from 10 to 1 up to 20 to 1. This shows that 

 lichens, compared with seed-plants, contain very little water at 

 any time, though the former are much more able to absorb 

 water or water vapor in the proportions needed than are the 

 latter, according to the experiments of Spalding. It must be 

 further stated that Jumelle found a Collema dipped in water to 

 show the surprising proportion of 35 to 1. He therefore con- 

 cludes that the gelatinous lichens have a very high absorbing 

 power. But these aside, lichens need very little water and are 

 able to obtain all that is needed through the general surface, 

 instead of through specialized organs as roots; the power of 

 lichens to absorb water and water vapor through the general 

 surface being high as compared with the results obtained by 

 Spalding for the leaves and twigs of certain desert seed-plants. 

 All considered, it may be assumed until otherwise proven, that 

 lichens absorb at least a large proportion of the moisture needed, 

 directly from water vapor of the atmosphere and from water 

 falling upon them. However, so far as the writer can ascertain, 

 the statements made by Jumelle do not rest upon experiments 



