THE HISTORY OF ANATOMICAL SCIENCE 323 



gation among the lower groups of the animal 

 kingdom, especially the polypes, worms, star- 

 fishes, ascidians, Crustacea, and insects, brought to 

 light a great number of new facts of the same 

 order; and, in 1842, the Danish zoologist, Steen- 

 strup, collected all of them known at that time, 

 and applied to the phenomena the general formula 

 of the "' Alternation of Generations.' He was met, 

 at the outset, by a difficulty of nomenclature. In 

 the majority of cases, the one term, or the one set 

 of terms, of the alternation is sexless. The germs 

 from which its offspring are produced are not true 

 eggs and are uninfluenced by males. Therefore, 

 it is obviously inexact to call these proliferating 

 forms ' females.' Steenstrup got over the difficulty 

 by terming them ' nurses ; ' though, thereby, he un- 

 doubtedly somewhat strained the usually admitted 

 attributes of a nurse. I do not imagine that 

 Steenstrup supposed that he had contributed 

 anything towards the explanation of these re- 

 markable phenomena by the nomenclature he 

 proposed. However this maybe, his work was of 

 much use by drawing the attention of biologists to 

 their general nature, no less than by bringing into 

 one view all the various forms of proliferation 

 which are exhibited by living matter, and all the 

 physical and metaphysical difficulties, with which 

 the problem of animal and vegetable individuality 

 bristles. Objections might be raised to the term 

 ' Parthenogenesis,' used by Owen, not merely for 



Y 2 



