158 SECRETS OF EARTH AND SEA 



not only as to the various kinds of wheel animalcules 

 (which now number not less than 900 species), but also 

 with regard to the minutest details of their structure, 

 their growth from the egg, and their habits. Another 

 English lover of these minute creatures, Dr. C. T. Hudson, 

 of Clifton (Bristol), began his observations a few years 

 later, and also discovered many wonderful kinds. It 

 was my good fortune to bring these two devotees of the 

 Rotifera, or Wheel Animalcules, together, and to induce 

 them to write a conjoint work on their favourites — after, 

 as they say in their preface, they had each continued 

 their studies almost daily for thirty years, and had made 

 innumerable drawings from living specimens, which are 

 reproduced in the many hundred (mostly coloured) figures 

 engraved in the thirty-four quarto plates of their monu- 

 mental book. This was published in 1889, a year after 

 Mr. Gosse's death at the age of 78. My friend, Mr. 

 Edmund Gosse, the distinguished man of letters, is the 

 son of the naturalist ; the microscope, the aquarium, and 

 the rock-pools of the seashore were the familiar delights 

 of his boyhood, as of mine. 



In Fig. 34 I have sketched the common Rotifer or 

 wheel animalcule. It is about the one-fortieth of an inch 

 long. The two specimens drawn in Figs. 34, A and B, are 

 seen to be clinging by the forked tail-end of the body to 

 a piece of weed (drawn in dotted lines). The body is 

 stretched in these specimens to its full length. It can be 

 shortened by a " telescoping " or pulling in of either end, 

 so as to make the animal a mere oval particle. The four 

 narrower joints or segments at the tail-end can be pulled 

 in like the segments of a telescope, whilst the two wheels 

 and adjacent .parts can be drawn down into the body as 

 shown in Fig. 34, C, where the two wheels (W) are seen 

 showing through the skin by transparency. 



The common rotifer can walk like a looping caterpillar 



