n8 STUDIES IN INSECT LIFE, ETC. 



and thence across to the Irish coast, and as a 

 result he came to the conclusion that these very 

 minute organisms, which pass with ease through 

 the meshes of the finest silk nets, are far more 

 abundant than any others in the open sea, whilst 

 the larger Diatomes and the Peridineae appear 

 comparatively scanty in numbers although rich 

 in species. 



Dr. Gran made a very careful investigation 

 as to the depths to which the surface algae sink, 

 the algae which are the ultimate food supply for 

 all the fauna of the sea. Samples were regu- 

 larly taken from the surface and at depths of 10, 

 25, 37i, and 50 fathoms below the sea level. At 

 depths greater than 50 fathoms algal life was 

 extremely scanty. The maximum algal life ap- 

 pears to lie somewhere about 25 fathoms, which 

 corresponds with what Lohmann had found to be 

 the case with the Mediterranean Coccolitho- 

 phoridae. This further corresponds with 

 Schimper's observations made in the Antarctic 

 during the " Valdivia " expedition. He found 

 that the maximum of algal life lay between 20 

 and 30 fathoms, that it totally disappeared below 

 100 fathoms, and that the great bulk lay above 

 the 50-fathom level. 



