April. 1019.] THE GERMINATIOy AISD DEV'ELOPMENT. 7& 



From the tables above shown wc can perceive that the winter 

 littoral formation w^ill be held in the belt between 0.900 m. 

 and 2.000 m. At noon of 8th August, 1917, the tide-gauge 

 was read 1.650 ra. Taking the water level at this moment as 

 starting point, it was easily measured that the experiment 

 ground needs to be not less than 0.750 m. (1.650 m. -0.900 m.) 

 in height above the said level. 



The first aim of the present experiment was to ascertain 

 the season when spores of the " rock-porphyra " settle on the 

 substratum ; and what level is best suited for the growth of 

 the plant. 



It is well known to us that stones of suitable size and 

 quality are the best substratum to grow the "rock-porphyra" on. 

 The Tcef chosen, however, is to be swept by furious surfs during 

 winter time. The stones to be laid over there must be of a 

 considerable weight to resist the powerful agency. The height 

 of the proper formation of the plant will be satisfactrorily deter- 

 mined provided that the substrata of the same character be 

 placed at different levels under possible similar conditions. 



After a careful consideration on these points, I deter- 

 mined to build a block of the concrete work with gravels and 

 Portland cement upon the reef chosen. The base of the block was 

 oblong in the general outline, height 4 feet^ general inclination of 

 the side slanting at about 45°, leaving a narrow platform on 

 the top. The surface of the block was smoothed with a trowel 

 (Text-fig. 1). 



The side of the block was divided into four horizontal 

 zones at each foot, with a terrace of 3 inches wide around the 

 block at each zone. On the terraces 60 knobs, made of the 

 same ingredients as the block, were cemented. These knobs 

 were numbered and could be knocked off the terraces by a light 

 hammer. The keeper of the Marine Station was instructed to 

 send, if necessary, a required knob at a required time knocking 

 it of^' carefully as to give no harm to the plants on it. Thus 

 I was able to study the spores of Porphyra attached to the 

 substratum at various levels without visiting the ground at 

 each time. (Text-fig. 1). 



