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 
v/hich 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 
