The celebrated Linnæus left a detailed account of the method by which mussels were caught in Sweden nearly two centuries ago. He wrote: “In the summer season, if the water is shallow, the fishermen wade in the stream and gather the mussels with their hands. Should the water be deeper, they dive for the mussels and place such as they find in a vessel made of birch bark, which they carry with them. Sunny days are selected, because then they can see deeper into the water. But, should this not suffice, they traverse the river on rafts which are painted white beneath so that the bed of the stream may be illumined by the reflected light. The men lie prone on the rafts and look down into the depths so that they may immediately seize with wooden tongs the mussels which they discover. Or else, hanging by their hands to the rafts, they seize them in the water with their toes. If the water is too deep even for this, they dive and feel around on the bottom with their hands until it becomes necessary to rise again to the surface in order to breathe. However, out of a hundred mussels, scarcely one contains a good pearl; but sometimes as many as twenty pearls of the size of a grain of sand are found in one shell. Many of the larger pearls are reddish or dark, but occasionally a beautiful white pearl is hidden under such a covering; although, naturally, it is rare that this is altogether perfect. It has been noted that mussels seven years old contain pearls; and in each of two mussels eighteen years old, a pearl was found attached to the shell.”[230] The list of streams in Sweden from which pearls were taken, as noted by Olaf Maimer, J. Fischerstein, and Gissler[231] a century and a half ago, seems to cover nearly all the rivers and brooks which flow from the mountains of this beautiful country. In Russia the love for the pearl has been almost as great as in Persia and India. During the Middle Ages, pearls were worn upon the clothes of nearly all well-to-do Russians. The great head-dresses of the women were ornamented with them; and they were used in decorating the stoles, vestments, crosses, and the priceless relics in the churches. The pearl-mussel is found in very many of the Russian streams. It occurs throughout Archangel, in most of the rivers which flow into the White Sea, into Lake Ladoga, Lake Onega, and the Baltic Sea; and likewise in the Volga watershed. Von Hessling states that east of the Volga its southern boundary extends to Lat. 56°, while on the west it extends further southward, so that in the region of the Dnieper it reaches Lat. 51°. The extreme southern limit is near the mouth of the Don, about 47° north latitude.[232]