FLOATING TIMBER 65 



Several tons have been removed from one 

 ship. 



Vast quantities of floating timber that 

 would, under ordinary conditions, seriously 

 interfere with marine commerce is rendered 

 heavier by barnacles and other creatures, and 

 sinks to lower depths. This department of 

 marine life has been more fully dealt with 

 in Nature Curious and Beautiful. 



The illustration (Fig. 14) is from a dark- 

 ground photo-micrograph, showing the object 

 as if amplified to 36 diameters. The time of 

 exposure was 15 minutes; the objective used 

 was the 1J inch, and the focal distance was 

 52 inches. 



Spines of Echini. 



To appreciate the complex structure and 

 the beauty of the spine or spike of a sea- 

 urchin, it will be necessary to give a little 

 attention to the plates which make up the 

 shell or ' test,' and also to the tubercles. 

 The shell consists of a number of plates 



5 



