136 



ROBERT L. FERNALD 



FiGUBE 5. — Distribution system, water tables, and aquariums. 



Experience lias indicated that the best 

 method of removal of excessive growth is 

 by mechanical cleaning of the lines. Fresh 

 water, hot or cold, and acids have proved 

 to be too slow and inefficient to eliminate 

 this growth, and a simple dismantling of 

 certain of the joints followed by pulling 

 of various-sized rubber stoppers through 

 the line has proved more satisfactory and 

 constitutes a less-timerconsuming inter- 

 ruption to service. Such a cleaning is re- 

 quired annually throughout the system 

 and more frequently in certain sections. 

 Excessive growth of diatoms within the 

 glass lines has been controlled with some 

 success by covering the lines with sheets 

 of aluminum foil. 



In evaluating the systems which we now 

 have in operation at the Friday Harbor 

 Laboratories, there is no question but that 



the combination of a pump lined with hard 

 rubber, a well-insulated line of Pyrex glass 

 pipe coupled by rubber gaskets, a receiv- 

 ing tank with glass lining, and sea-water 

 tables and aquariums of wood or plexiglass 

 give assurance that the system will deliver 

 water with physical characteristics as 

 nearly like those of the water at the source 

 where the intake operates and as free from 

 contamination with heavy metals as can 

 be desired. In a laboratory such as ours, 

 where the demands for sea water are such 

 that not only must a copious supply be 

 maintained but also it must be nearly the 

 temperature of the channel water and as 

 free from contamination or toxic agents 

 as possible to assure optimal culture con- 

 ditions for everything from embryos of 

 invertebrates to various algae and fish, the 

 glass systems which we have are excellent. 



