Seaweed and its Uses. 315 



Japanese from time immemorial have recognized the value 

 of seaweeds in agriculture ; but as the population of those 

 countries became more numerous, and the adoption of the 

 algEE as a healthy food became better known, they at- 

 tained a higher value, and their employment as a fertilizer 

 was to a great extent replaced by other substances, espe- . 

 cially the excreta of towns. In Japan seaweed is often 

 carried to the slopes of mountains to form humus to 

 nourish trees. 



The services rendered to agriculture by seaweeds are 

 well known and very important. Buried in the earth, they 

 are converted by fermentation into an excellent humus, of 

 great sei-yice to plants, and the cultivators on the coasts 

 of many countries carry away thousands of cartloads. 



At Granville, in France, there is a large commerce in 

 seaweed. The value of that used for manure cannot well 

 be determined. 



In France the collection of seaweed is only allowed at 

 certain fixed periods, while in China and Japan it is carried 

 on daily. Still, the former, plan may have its advantages, 

 as it is known that it is in the midst of this exuberant 

 vegetation of marine plants many species of shell-fish, such 

 as mussels, scallops, etc., live. It is also the spawning 

 ground of a certain number of fish ; and, finally, here the 

 young fry and the Crustacea find a shelter from the voracity 

 of the large species of fish with sharp teeth, such as the 

 congers, bonitos, etc. 



The seaweeds form in the Atlantic considerable banks, 

 especially in the part known as the Gulf Stream. There 

 ships pass through large spaces entirely covered with them. 

 Sometimes the banks take the form of long serpents, the 

 two extremities of which cannot be seen. To these accu- 

 mulations of plants the sailors give the name of Neptune's 



