214 THE MINUTE ANATOMISTS 



Rotifers ^ 



Having macerated bruised pepper in rain-water, Leeu- 

 wenhoek found animals of the kind which we now call 

 rotifers in the infusion ; the description agrees with that 

 of Eotifer vulgaris, but few details are furnished. He 

 observed that the tail-end was furnished with a forked 

 grasping apparatus, the head-end with a peculiar organ 

 which set up whirlpools in the water. The animalcules 

 were able to creep like leeches, attaching each end by 

 turns to the supporting surface. Near the middle of the 

 body was a structure which seemed to pulsate, and was 

 taken by Leeuwenhoek for the heart, but it was no 

 doubt the mastax, or gizzard. 



Fifteen years later Leeuwenhoek returns to his 

 rotifers.^ In a leaden gutter the rain-water took a 

 reddish colour, and when examined by the microscope 

 was found to contain red or green rotifers. Some con- 

 tained embryos, one of which was seen to free itself and 

 swim about. Hot weather came on, and the gutter 

 dried up. When all the water disappeared there was no 

 sign of life, but it occurred to Leeuwenhoek to put a 

 little of the dry mud into a glass tube and add rain- 

 water. In an hour rotifers were seen clinging to the 

 glass or swimming about in the water. They revived 

 equally well when boiled rain-water was used to moisten 

 the mud, and even after the mud had been kept dry for 

 twenty-one months. 



Leeuwenhoek sagaciously remarks that the cuticle of 

 the animalcules must be singularly impervious to water, 

 for if the tissues had really become dry they must have 

 perished. The possibility that minute organisms may be 



1 Cont. Ep. (1687). Vol. II, pp. 94-6. 



^EpiHt. 144, Cont. Arc. Nat. (1702). Vol. Ill, pp. 380-394; Phil. Trans., 

 Nos. 283, 296, 337 (1703-13). 



