I Have adopted the name “Pseudospora volvocis” for the protozoon here discussed, as the two most obvious phases correspond with the creature described under that name by Cienkowski.
Pseudospora was noticed amongst Volvox, supplied by Mr. T. Bolton to the Cambridge laboratory and, later on, to Glasgow. As the creature showed features of considerable interest and the knowledge of its life history appeared to be very imperfect, it seemed advisable to make it the subject of special investigation.
I wish here to acknowledge my great indebtedness to Professor Graham Kerr. This paper, which was begun at his instigation, would certainly never have been completed but for his kind supervision and guidance.
All the processes described were followed out on the living specimens and checked by stained preparations. The investigations were made for the most part on material mounted on slides under cover-slips supported with wax. It was impossible, however, to...
