132 THE AMERICAN MONTHLY [May 



in the retina analogous to the rods and cones of the hu- 

 man retina. Dr. Weir rightly considers this "unique and 

 very wonderful." He goes on, "When playing 'tag' this 

 minute animal is directed in the pursuit of its fleeting 

 playmate by sight, and not by another and analogous 

 sense. While at play one of these little creatures will hide 

 behind a small pebble or a bit of alga ; when one of its 

 playmates approaches, it will suddenly dart out upon the 

 unsuspecting passer-by and greatly startle it. Their ac- 

 tions are so evidently innocent sport that the most casual 

 and obtuse observer cannot mistake them for anything 

 else." After this remark we accept with gratitude the fur- 

 ther statement, "When we take into consideration the fact 

 that this animalcule is almost microscopic in size, and that 

 it is of very low organisation, this habit of amusement 

 seems very wonderful indeed." 



This interesting note called forth in the "English Me- 

 chanic" the following letter, signed, "C. F. R., " in which 

 initials it is not difficult to recognize a well-known author- 

 ity on rotifers : — "Dr. Weir's note on the remarkable 

 sportive habits of Melicerta might be supplemented with 

 other more wondrous feats of this wonderful rotiferon. 

 Any one who has seen this helpless, awkwardly swim- 

 ming creature when it has had the misfortune to become 

 detached and to be driven out of its tube will be much in- 

 terested to hear that it can dart about in and out of its 

 house, hide behind grains of sand with one eye over the 

 edge or round the corner, and do other frisky gambols. 

 Dr. Weir might well have added that, with a little per- 

 severance and a grain or two of imagination, Melicerta 

 can be seen to use its foot as a prehensile organ ; in fact, 

 like an elephant his nasal trunk. When a small rotifer 

 of the genus Rattulus or Mastigocerca comes by, Melicer- 

 ta will seize it, break off its long pointed toe, and use it 

 as a toothpick to clean its teeth, of which it has quite a 

 number, quietly siting the while on the above-mentioned 



