INTRODUCTION. 11 



coitus, but Mr. Gosse bad this good fortune in the case of a closely allied species, 

 B. pala. He says : 



" I collected about a dozen females, half-grown and adult, and placed with them two 

 lively males that had been hatched during the night. I directed my attention principally 

 to one of these, as I could not watch them both. It soon came near one of the females, 

 when it seemed to become animated by a sort of frenzy ; describing with excessive 

 rapidity a circle, of which its head formed the circumference and its foot the centre. The 

 extremities were incurved in the direction of its circular movement. After a while it 

 left off, and began to play about the body of a female, moving over and round the lorica, 

 while she whisked about the foot, as if to lay hold of him ; at length she drew in her 

 foot, and that of the male appeared to adhere to it ; and I distinctly saw the thick penis 

 presented to the cloaca, and for a moment inserted about half its own length ; then it 

 was instantly drawn out, and the male began his frenzied gyrations again." ' 



It is obvious, even from the brief account here given, that several highly interesting 

 questions arise concerning the reproductive system of the Eotifera. For instance, in what 

 respects, besides outward form and covering, do the ephippial eggs differ from the smooth 

 female eggs ? and what leads to their production ? 



What part, if any, does the male play in these differences ? and how is it that one 

 female produces none but male, while another has none but female eggs ? 



Again, why are the males of so strange a structure ? and why do they appear only for 

 a short time during the year ? and is their appearance due to external causes, or are 

 they the inevitable completion of a cycle of reproductive changes ? 



Unfortunately it is much easier to ask these questions than to answer them. The 

 observations that have been made on these points are but scanty ; and, to some extent, 

 contradictory ; and the difficulties in the way of persistent investigation are by no means 

 slight. 



1 " On the Dioecious Character of the Rotifera." Phil. Trans. 1857, % 10. 



