SOME MICROSCOPIC MUMMIES. 131 



a great number of animalcules, some of them red, and 

 others of them green. The largest of these, viewed 

 through the microscope, did not appear bigger than a 

 large grain of sand to the naked eye ; the size of the 

 others was gradually less and less. They were, for 

 the most part, of a round shape, and in the green ones 

 the middle part of their bodies was of a yellowish 

 colour. Their bodies seemed composed of particles of 

 an oval shape. They were also provided with certain 

 short and slender organs or limbs, which were pro- 

 truded a little way out of their bodies, by means of 

 which they caused a kind of circular motion and current 

 in the water : when they were at rest and fixed them- 

 selves to the glass, they had the shape of a pear with 

 a short stalk." 



So far, quaint old Leeuwenhoek. What he saw 

 in 1702 and discovered in that year, any one may see 

 and admire to-day. For the species of animalcule 

 he described was the common " wheel-animalcule," or 

 Rotifer vulgaris, as it is scientifically named. This 

 animal forms a capital study for a young microscopist. 

 As shown forth in our illustrations, its main features 

 agree tolerably well with the description of the old 

 Dutch naturalist. The " certain short and slender 

 organs or limbs " which he noted as being " protruded 

 a little way out of their bodies," and as causing currents 

 in the water, were the so-called " wheels " from which 

 the animalcules receive their familiar name. These 

 " wheels " may be seen at the head of the animalcule 

 (figs. 27 and 28), fringed with delicate lashes or cilia, 

 of the delicacy of which no drawing can give any idea. 



The cilia are threads of living protoplasm, which on 

 their own account keep up a perpetual vibratile motion, 

 as in the gills of the oyster and mussel, and in the 



