CH. V] LAMINARIA. 113 



(128) Increase of size not uniform in direction. 



Cut a rectangular piece out of the thallus of Laminaria, 

 choosing a part free from wrinkles ; let it be slightly 

 oblong so that the longitudinal axis of the thallus may be 

 distinguishable. Measure the length and breadth with a 

 millimeter scale and mark, by means of a pin-hole in the 

 corner, the two edges along which the measurements were 

 taken. Place it in water and measure it again in a 

 quarter of an hour. It will be found to have increased far 

 more in the transverse than in the longitudinal direction. 



(129) Effect of temperature 1 . 



Weigh, to O'l gram, about 30 grams of air-dried peas : 

 place them in water at about 26 C., and let them remain 

 at that temperature for 2 hours. Dry them first with a 

 soft cloth, then with filter-paper, and weigh them again. 

 Place at the same time a similar weight of peas in water 

 at 10 14 C. and compare the gain in weight in the two 

 cases. The peas, which have been in warm water, will 

 have absorbed from two to two and a-half times as much 

 water as the second lot 2 . 



(130) Salt solution. 



Weigh about 30 grams of peas, taking care to use the 

 same material as that employed in experiment 129 ; place 

 them in 10 per cent. NaCl solution, which must be kept 

 at the same temperature as the cool water in experiment 



1 See Keinke in Hanstein's Botan. Abhand. iv. 



2 According to Nobbe (Handbuch der Samerikunde, 1876, p. 230) the 

 effect of temperature is not very apparent when peas are soaked for longer 

 periods. 



D. A. ft 



