VII.] ANIMALS AND PLANTS. 165 



at length. But, in the first place, in order that I may 

 conveniently distinguish this " Monad " from the 

 multitude of other things which go by the same 

 designation, I must give it a name of its own. I 

 think (though, for reasons which need not be stated at 

 present, I am not quite sure) that it is identical with 

 the species Monas lens, as defined by the eminent 

 French microscopist Dujardin, though his magnifying 

 power was probably insufficient to enable him to see 

 that it is curiously like a much larger form of monad 

 which he has named Heteromita. I shall, therefore, 

 call it not Monas, but Heteromita lens. 



I have been unable to devote to my Heteromita 

 the prolonged study needful to work out its whole 

 history, which would involve weeks, or it may be 

 months, of unremitting attention. But I the less re- 

 gret this circumstance, as some remarkable observa- 

 tions recently published by Messrs. Dallinger and 

 Drysdale 1 on certain Monads, relate, in part, to a form 

 so similar to my Heteromita lens, that the history of 

 the one may be used to illustrate that of the other. 

 These most patient and painstaking observers, who 

 employed the highest attainable powers of the micro- 

 scope and, relieving one another, kept watch day and 

 night over the same individual monads, have been 

 enabled to trace out the whole history of their Heter- 

 omita ; which they found in infusions of the heads of 

 fishes of the Cod tribe. 



1 " Researches in the Life -history of a Cercomonad : a Lesson in 

 Biogenesis ;" and " Further Researches in the Life -history of the 

 Monads." "Monthly Microscopical Journal," 1873. 



