The President's Address. By Dr. G. T. Hudson. 
11 
female, that had laid no eggs before intercourse with the male ; and, 
in both cases, she laid ordinary female eggs. 
(6) Plate has seen the hatching of two epliippial eggs of 
Hydatina senta , and Joliet one of Melicerta ringens, and in each 
case the ephippial egg produced one female. 
It is probable then, from the statements above, that the ephippial 
egg is not due to the action of the male ; but that it is the termina- 
tion of that budding process, by which virgin females produce virgin 
females through many generations, and that it is resorted to when 
the vigour of the ovary begins to fail, so that a single germ is no 
longer able to produce a living animal. When this time arrives 
many germs are separated off to do the work for which one is usually 
sufficient, and so combine together to produce one embryo for the 
next year. The double egg-shell with its deep cells, and various 
knobs or spines, may be due to a surplusage of material in this joint- 
stock egg-making.* 
Of the series, of which the ephippial egg is the end, it is probable 
that an ovary impregnated by the male is the beginning ; but this 
point, as well as the doubts that yet linger about the above account, 
could surely be cleared up by patient experiment. 
It would be easy, for instance, to isolate, as soon as it is hatched, 
a female of each succeeding generation of a Hydatina senta , and to 
see how many generations may be thus produced ; and whether the 
series invariably ended in a female laying ephippial eggs. There 
should bo, moreover, two such series ; one commencing with a female 
impregnated before she had laid any eggs, the other with a virgin 
female. As Hydatina senta is a common, large, and very prolific 
Kotiferon, as well as one that may be easily fed with Buglense , &c.,the 
experiment would not be very troublesome. Possibly, too, such 
experiments might throw some light on the causes that give rise to 
the laying of male eggs ; about which at present we do not seem to 
know anything. 
There are two other points in the reproduction of the Botifera 
which are puzzling. The first occurs in Botifer vulgaris and its 
allied forms. In these the eggs drop off the ovary into the perivis- 
ceral cavity, and are hatched within the animal ; and the young 
rotifer seems to lie free in the cavity, for it can stretch itself to its 
whole length, or twist round and reverse its position without apparent 
hinderance from any inclosing membrane. In the act of birth it has 
been seen to pass through the cloacal aperture ; and one observer 
noticed a young Botifer vulgaris protrude its head, expand its 
wheels in the water, and then furl them and shrink back within the 
* M. Joliet’s observations on the hatching of the ephippial egg of Melicerta 
ringens (Comptes Kendus, xciii. (1881) p. 856) point in the same direction. For he 
noticed that the young female hatched from the ephippial egg had the perfect form 
of the adult Melicerta , and was therefore in an advanced stage of growth compared 
with the young hatched from the ordinary thin-shelled egg. 
