464 Beard. — Reproduction in Animals and Plants . 
animal development is accomplished, and that the alternation 
solution has been persistently stuck to, in spite of the fact 
that it was almost universally ignored, or, where noticed, 
looked upon as absurd. 
My own researches have been sufficiently laborious and 
costly in time and money, without the additional burden of 
new investigations into, for instance, the conjugation of the 
Infusoria. With such works as those of R. Hertwig, and 
still more, of Maupas to fall back upon, one is relieved from 
anything but the utmost acknowledgement of what is due to 
them. If these researches had offered serious obstacles to 
the further elucidation of the problem, two courses would 
have been open. The views might have been dropped as 
probably erroneously based, or new researches might have 
been attempted. In many ways I consider myself as fortunate 
in having had the track cleared, and all the serious work done, 
by such distinguished observers. 
Maupas’ diagram of the conjugation of Vorticella , repro- 
duced in woodcut 13, yields at a glance abundant evidence de- 
monstrating the intricate nature of the process. Complicated 
as are the phenomena which ensue on conjugation, their 
explanation, as processes solely concerned in the formation 
and differentiation of new individuals, furnished with macro- 
and micro-nuclei, will hardly be challenged. 
The two divisions B and C of the micro-nucleus of the 
c macro-gamete 5 are also simply explicable, for they differ in 
no respects from corresponding ones leading to spore-forma- 
tion and reduction in other forms. Of the four spores (c) 
produced three are abortive, whilst the fourth, representing 
the sporozooid, divides (D) as in other cases, once. Owing 
to the circumstance that the other individual, the micro-zooid, 
has become reduced in size, and has lost all power of recep- 
tivity for a conjugating gamete, the one (d 1 ), which in the 
ancestry performed the functions of a ‘ wandering nucleus ’ 
passing over to what is now the micro-zooid, no longer 
possesses functions and undergoes atrophy. It is still 
formed, because its formation is a necessary incident in the 
