Opalina. 197 
page 
PRISTON PTOGLIGIOR ete cri MOM EE ou are Mert iiss ig i! eal 5 ae (ak ell Ue ac CEOS 
PRICE MIDE UETEPUNGNG ER ty ve as cee ee 88s ce er aa ds pee ae ene 
Description of O. zellert . . POS Fee 
Chronological review of the litera thie at Orattha,\ 319 
Appendix. Table showing the staining reactions of the Gifarent, saris 
Ob PRE HOUwAOL DARE oe ede le thts viseae acl Sa gk cbarele beta Wn wee 
Pcen ibe WOO ce le ME Kuehne eee tet) ca sue a) oe Ae Ok, ee eicer (na 
ER IGNOMIGH DE PAGRES 8s. ccc e aneg Ske es , 0 8 ry oR en Pele 
Acknowledgements. 
The work upon which this paper is based has been done in 
the Zoological Institute in Wiirzburg. Professor Boveri directed 
my attention to the favorable character of Opalina caudata for cyto- 
logical study, and suggested also that it would be interesting to 
compare the reproductive processes in this binucleated species with 
the phenomena of reproduction which NerrEsHEIMER had then 
recently described for O. ranarum and O. dimidiata, both multi- 
nucleated forms. I cannot adequately express my thanks to Professor 
Boveri for these suggestions and for the constant advice he has 
given during the course of the work. I am especially indebted 
to him for suggestions in regard to the comparative cytological part 
of this paper. 
Professor SpEMANN kindly shared with me larvae of Rana esculenta 
which he had reared for experimental study. To Dr. Lo Branco 
and the Director of the Zoological Station in Naples | am much 
indebted for material preserved and sent me. Dr. J. WiLHELMI gave 
me material of Gunda segmentata infected with Hoplitophrya uncinata 
which I desired to compare with its reputed relative Opalina, He 
also most kindly lent me many of his series of sections of this 
Turbellarian, that I might study the parasites. Dr. F. Bauzer 
preserved material of Opalina for me daring two months in the 
early spring when I was away from Wiirzburg, and, during my 
absence in the summer, Mr. E. Scunerpr did me a similar service. 
Mr. W. B. von Barner kindly lent me a fine preparation of sections 
of O. ranarum in the rectum of a tadpole of Rana temporaria, the 
only preparation I have had showing zygotes of this species. ‘To 
all of these, who have so greatly helped me in obtaining material 
for study, I wish to express my most hearty thanks. 
14* 
