PAPILIONIDiE — BUTTERFLIES. 223 



Swammerdam relates that, one morning in 1610, great 

 excitement was created in the Hague by a report that the 

 lakes and ditches about Leyden were turned to blood. 

 Florence Schuyl, the celebrated professor of physic in the 

 University of Leyden, went down to the canals, and taking 

 home a quantity of this blood-colored matter examined it 

 with a microscope, and found that the water was water still, 

 and had not at all changed its color ; but that it was full of 

 small red animals, all alive and very nimble in their motions, 

 the color and prodigious numbers of which gave a reddish 

 tinge to the whole body of the water in which they lived. 

 The animals which thus color the water of lakes and ponds 

 are the Pulices ai^borescentes of Swammerdam, or the 

 water fleas with branched horns. These creatures are of a 

 reddish yellow or flame color. They live about the sides of 

 ditches, under weeds, and among the mud ; and are there- 

 fore the less visible, except at a certain time, which is in the 

 month of June. It is at this time these little animals leave 

 their recesses to float about the water, and meet for the 

 propagation of their species; and by this means they be- 

 come visible in the color which they give to the water. The 

 color in question is visible, more or less, in one part or 

 other of almost all standing waters at this season ; and it is 

 always at the same season that the bloody waters have 

 alarmed the ignorant.^ 



The prodigy, mentioned by Livy, of a stagnating piece 

 of water at Mantua appearing as of blood, was no doubt 

 owing to the appearance of great numbers of the Pulices 

 arborescentes in it.^ 



Concerning the origin of bloody rain, Swammerdam en- 

 tertained the same idea as Peiresc ; but he does not appear 



1 Swam. Hist, of Lis., Pt. I. p. 40. 



2 Cf. the foUowiug verses from Ex. vii. 19: <'And the Lobd spake 

 unto Moses, Say unto Aaron, Take thy rod, and stretch out thine 

 hand upon the waters of Egypt, upon their streams, upon their rivers, 

 and upon their ponds, and upon all their pools of water, that they 

 may become blood; and that there may be blood throughout all the 

 land of Egypt, both in vessels of wood and in vessels of stone. 



"20. And Moses and Aaron did so, as the Lord commanded; and 

 he lifted up the rod, and smote the waters that were in the river in 

 the sight of Pharaoh, and in the sight of his servants; and all the 

 waters that were in the river were turned to blood." 



