THE REPRODUCTION OF THE INFUSORIA. 565 



Infusoria by the investigations of Engelmann, 1 Biitschli, 2 

 and Hertwig, 3 the results of whose observations may be 

 summed up as follows : 



1. The so-called acinetiform embryos are parasites. 



2. The rod-like bodies occasionally observed in the endo- 

 blast are also parasites, and probably Bacteria. 



3. The globular so-called germs in the Vorticellidce and 

 the bodies termed "ovules''' by Balbiani have nothing to do 

 with reproduction. 



4. In the Vbrticellidce, when conjugation takes place, the 

 endoplasts of both individuals break up into a number of 

 fragments. These become mixed up in the common body 

 which results from conjugation. The endoplast of the latter 

 results from the gradual union of many smaller particles 

 which make their appearance in the endosarc. Whether 

 they are identical with the fragments into which the endo- 

 plasts of the conjugated individuals have divided, is not cer- 

 tain. 



5. When Infusoria which possess an endoplastule, as 

 well as an endoplast, conjugate, both of these structures un- 

 dergo division ; and the endoplastule, before division, ac- 

 quires the striated structure and spindle shape, which has ob- 

 tained for it the name of " seminal capsule." 



6. The final result of conjugation is the appearance in 

 each of the individuals which have undergone conjugation 

 of the endoplast and endoplastule (either single or multiple) 

 which characterize the species. 



It does not appear that there is any positive proof that 

 the striated endoplastule, or endoplastules, of the conjugated 

 individuals are or are not exchanged. From Butschli's obser- 

 vations on Stylonichia mytilus, he concludes that the endo- 

 plast divides into four fragments ; that these round them- 

 selves off into the so-called " ovules " of Balbiani, and are 

 expelled from the body ; while, of the four striated endoplas- 

 tules into which the endoplastules which exist before fecunda- 

 tion divide, one is converted into a large transparent body, 

 and, dividing, gives rise to the two new endoplasts which ap- 

 pear in the Stylonichim, after their separation. Two of the 

 others become the new endoplastules ; while one, apparently 



1 " Ueber Entwickelung und Fortpflanzung der Infusorien." ("Morpho- 

 logisches Jahrbuch," 1876.) 



2 " Mittheilungen fiber die Conjugation der Infusorien und die Zellthei- 

 lung." ( Zeitschrift fur iviss. Zoologie, 1875.) 



3 " Ueber Podophrya ge?nmipa?'a, nebst Bemerkunoren zum Bau und zur 

 systematischen Stellung der Acineten." ("Morph. Jahrbuch," 1876.) 



