BALBIAMj OX SEXUAL REPRODUCTION IX THE INFUSORIA. 177 



Stein, thougli it met with less favour at the hands of other 

 observers. And tlie late Johannes ]\Iiiller, with some of his 

 most able pupils, took note of various minute filaments seen 

 by them within the bodies of several Infusoria, which fila- 

 ments they were disposed to regard as spermatozoa. Such 

 researches and conjectures, in themselves by no means useless, 

 were very far from settling the questions really at issue ; for 

 it has now conclusively been shown that the nucleus does 

 not perform the function of a testis, and that Miiller's fila- 

 ments were, in all probability, parasitic organisms, belonging 

 to the lower Algae. 



Now, however, the whole aspect of this subject has been 

 changed, and for the vagueness which, less than four years 

 ago, characterised all attempts to explain the generative 

 functions of the Infusoria, has been substituted that clear and 

 complete survey of their leading phenomena, which science 

 has just received from the pen of M. Balbiaui. In his excel- 

 lent summary, just brought to a conclusion, a concise, yet 

 sufficiently detailed account is given of the structure of the 

 sexual apparatus, male and female, among the principal sub- 

 divisions of the class. The changes Avhich this apparatus 

 undergoes in the course of its development — the evolution of 

 the essential elements to which it gives rise, and many other 

 particulars of interest, are all in their turn described with 

 laudable minuteness and precision. Compelled, at times, to 

 correct the mistakes of others, he in no wise shrinks from 

 avowing the errors into which he himself fell at the com- 

 mencement of his inquiries; nor does he hesitate to point 

 out the difficulties of interpretation which beset him at each 

 successive stage of their progress. Perhaps future investi- 

 gators may, in some degree, require a more qualified state- 

 ment of views which INI. Balbiani, in common with most of 

 his readers, now considers as beyond the reach of cavil. Yet, 

 even with this restriction, it does not seem too much to say 

 that a single observer has done more to establish on a secure 

 basis a right knowledge of the sexual phenomena of the In- 

 fusoria than the collective body of his predecessors in the 

 same field of inquiry. 



We shall^ therefore, without further preface, proceed to 

 lay before our readers the chief facts and opinions of M. 

 Balbiani's mei—oirs, Avhenever the occasion demands it, 

 translating the very words of their precise enunciator. 



Parts of the Reproductive System. 

 The Infusoria are hermaphrodite, but not self-impreg- 



