The Life-history and Cytology of Polyphagus 
Euglenae. 
BY 
HAROLD WAGER, F.R.S. 
With Plates XVI-XIX. 
Introduction. 
O UR knowledge of this very interesting member of the Chytridiaceae 
is due to the investigations of Gros (’51), Siebold and Meissner (’55), 
Bail (’55), A. Braun (’55, ’56), A. Schenk (’57), and especially Nowakowski 
(’76), who has given the most complete account of its general structure and 
life-history as observed in living specimens. 
Nowakowski mentions (’76) that it was first of all described by A. Braun 
and Bail as Chytridium Euglenae. Subsequently Schenk, regarding the 
organism as two-celled, separated it from Chytridium and placed it in 
Rhizidium , but Nowakowski found that it differed in so many particulars 
from the genera Chytridium and Rhizidium that he felt himself justified in 
placing it in a new genus under the name Polyphagxts. 
The cytology of Polyphagus has received little attention. In 1898 
I gave a brief account of the structure of the nuclei and of their behaviour 
during the formation of the zygote, and made further references to it in 
papers subsequently published (’99 and ’05). Dangeard (’00) in a longer 
memoir confirmed in general my results, and gave some additional details 
concerning the structure of the zygote and of the asexual sporangium and 
spores. During the last few years the cytology of various other members 
of the group has received attention, and the results obtained indicate that 
a careful study of the Chytridiaceae may give some clue to many interesting 
problems connected with sexuality and the function of the nuclei in 
fertilization, and may also throw some light upon the phylogeny of the 
Fungi. 
According to Schroeter (’92, ’93), the Chytridiaceae are divided into 
two very distinctly marked groups. In one, the resting spores are pro- 
duced asexually, seldom by copulation of swarm spores ; in the other, the 
resting spores are produced by the union of two vegetative cells. 
[Annals of Botany, Vol. XXVII. No. CVI. April, 1913.] 
O 
