TRANSACTIONS OF SECTION K. 



583 



About sixty specimens were obtained and established in pots, ranging from 

 4.1 to 7A inches, during March and April 1910, before the renewal of growth had 

 set in "At the end of June about forty were growing satisfactorily and these 

 were protected from rain by a light screen from July onwards When it was 

 apparent that wilting had set in, the peat or soil was sampled from among 

 the roots and air-dried. The table gives a digest of the results obtained, with 

 the exception of such as are not satisfactory from over drying or other causes. 

 The humus and water remaining in the soil are expressed in terms of the air-dry 

 soil The further loss at 100° is not entered. 



The ratio water/humus is a better index of the state of the soil than is the 

 water-content, for it shows less individual fluctuation. Comparison with its 

 normal value shows the following approximate relations to exist :— 



One-third of the water-content of peat is non-available in the 

 case of . . . Erica Tetralix Molinin, Pteris. 



One-quarter . . Deschampsia, Nardus. 



One-fifth . . . Calluna, in pure peat. 



One-sixth . . . Vaccinium, Myrtillus, Agrostis. 



One-seventh . . Eriophorum spp., Calluna, in sandy peat. 



One-ninth . . . Vaccinium Vitis-Iian. 

 The analyses also show the influence of the soil. Though not numerous 

 from this point of view, the water/humus ratio is highest in the case of a heavy 

 loam, and higher for a pure peat than a sandy peat. Conversely, the time taken 

 to produce wilting is longest with a sand and sandy peat, and shortest in the 

 case of loam. 



1 Over-dried. 



WEDNESDAY, SEPTEMBER G. 

 The following Papers and Eeports were read : — 

 1. On the Presence of Sugar in the Tissues of Laminaria, By S. Mangham. 



Laminaria digitata and L. saccharina have been examined for sugars at various 

 times of the year by means of Senf t's method of forming osazones. 



The material used was either sent in sea-water from Aberystwyth by Professor 

 Yapp, and examined as soon as received at Cambridge, or was gathered at the end 

 of March at Port Erin, Me of Man, and investigated at once at the marine 

 biological laboratory. 



Observations were made upon sections cut from the stipe, the region of new 



