CORRESPONDENCE. 67 



6. — Mr. Hoyle says that Faramcectum reproduces itself by 

 dividing down the middle. 



This was believed to be the case till 1858, when Balliani 

 showed that it was an error. Reproductive fission in Faramce- 

 cimii is always transverse, across, not down the middle. What 

 had previously been taken to be cases of reproductive, longitud- 

 inal fission, were then shown to be only cases of temporary 

 conjugation, which may last for several days. 



7. — In the account given of conjugation, the nucleolus of one 

 individual is said to combine with the nucleus of the other, and 

 vice versd. 



According to this theory, the nucleus and nucleolus function 

 as ovary and testes respectively, or true male and female 

 elements. This was asserted by Balbiani in 1878, and subse- 

 quently supported by other observers. But the recent researches 

 of Engelmann and Biitschli have rendered this theory more than 

 doubtful. According to these authors, as epitomised by Mr. 

 Saville Kent, the nucleus of each of the conjugating individuals 

 is entirely absorbed in the general body-sarcode, and by-and-by an 

 entirely new nucleus is formed by the assemblage of fragmentary 

 particles derived from the same body-sarcode. The old nuclei 

 in Stylo7iychia mytilus are broken into four fragments, and ejected 

 from the body. Biitschli holds that there is no essential 

 difference between the nucleus and nucleolus, the latter some- 

 times even developing into the former. 



8. — After conjugation, FaramcEcium is stated to give birth to 

 little bodies, which develop into sucker-bearing AcmetcB^ which 

 remain sticking to their parents and sucking their juices for a 

 while. These then develop into the parent form. 



This is Stein's old theory again, of 1854, since abandoned by 

 him and every one else. Mr. Hoyle's paper represents the state 

 of our knowledge about 25 to 30 years ago ; but much knowledge 

 has been gained since then with respect to these interesting 

 little creatures. 



J. G. Grenfell. 



To the Editor of the Journal of Microscopy and Natural Science. 



Sir,— 



I make no pretensions to being a specialist as regards the 

 Infusoria, and, in common with your readers, am obliged to 

 Mr. Grenfell for correcting any points in my lecture which may be 

 at variance with recent researches. I may remark, however, that 

 most of the statements which he has contradicted, are to be found 



