HUXLEY, ON CLASSIFICATION. 81 
body of the other. The spermatic filaments are said to enter the 
nucleus, which then enlarges, and either divides into, or gives off, a 
number of rounded germs, which become oval ciliated bodies pro- 
vided with long processes. These make their way out of the body, 
and, it is believed, are metamorphosed directly into young Para- 
meecia. But, perhaps, further information is required before we can 
be quite certain on this point. 
The subsequent lectures in this volume are devoted to 
the Molluscous, Annulose, and Vertebrate series of animals. 
They are treated in the same lucid and original manner as 
the lower groups of animals to which the above lecture 
relates. We can recommend these lectures to the study of 
all young students of natural history who are desirous of 
taking a comprehensive view of the structure and relations of 
the animal kingdom. In the second and third lectures, 
will be found numerous observations on the forms of the 
molluscous and annulose animals, which will clearly show that 
it is only by the aid of the microscope that a proper study of 
the animal kingdom can be undertaken. These lectures by 
Professor Huxley are copiously illustrated, and as a work 
by one of the most advanced students of the science of biology, 
it cannot fail to be interesting not only to those engaged in 
anatomical and physiological studies, but to all who take an 
interest in the observation of the structure and functions 
of the animal kingdom. 
