GRIER] THE FRESH WATER PEARL MAKERS 343 



the shells before the glochidia were ripe. Several states have passed 

 laws protecting the mussels at certain seasons of the year, and so 

 arranged as to protect the pearl button industry. Sentiment 

 should be crystallized among the people to the effect that a mussel 

 should not be killed unless the fullest use be made of all parts of it 

 as indicated herein. Broken shells may be ground up for feeding 

 to poultry. 



The scientific facts stated as probably affecting the coloration of 

 the shell, are in general those affecting the character of its growth. 

 Where lime, or its antecedent limestone is scanty in the water, the 

 shell is found to be quite thin, and in some cases, quite soft. Be- 

 yond stating that the beautiful painting and banding of the epi- 

 dermis seems more characteristic of the smaller creeks and rivers, 

 etc., no suggestion may be offered as to its significance, except, as 

 with the nacre, it represents a response to the environment. Upon 

 the above mentioned quaHties of the shell largely depends its 

 availability for button making, the more important economic use. 

 For a good quality of button, is required a shell of pure color, 

 neither too thick nor too thin, nor too hard to cut. The value of 

 the raw shells yearly collected for this industry approximates 

 $1,000,000; the finished product of course much higher. These 

 pearls, incidentally collected may range well up into the hundreds 

 of thousands of dollars. No public school should be without a 

 demonstration showing the steps of manufacture from the raw 

 material to the finished product. Such may often be obtained 

 from button manufacturers. The increasing scarcity of high 

 grade button material indicates that a rigid program of conserva- 

 tion must be adhered to. The variety of shapes and characters of 

 shell architecture has suggested the common names by which they 

 are known. Thus we have "pocketbook", (see illustration), "lady 

 finger, squaw-foot, wash board, maple leaf, three horned wart back, 

 elephant ear, butterfly, pistol grip, etc." The age of a shell may 

 often be determined by counting the rest from growth rings to be 

 seen upon it, but this is not always accurate. 



The fresh water mussels furnish outstanding examples of the 

 wonderful interrelations existing in nature, and how living things 

 are largely the product of their surroundings, living and non-living, 

 interacted upon by them and with them. Unlike their hardy 

 relatives the snails, they do not usually thrive in indoor aquaria, but 

 are susceptible to pond culture. Their further study quite bene- 



