THE DEVELOPMENT AND CYTOLOGY OF 
RHODOCHYTRIUM‘ 
ROBERT F. GRigecs 
(WITH PLATES XI-XVI) 
To the student of phylogeny, whether he be taxonomist, or 
morphologist, no organisms are as interesting as those which appear 
to occupy positions intermediate between the larger groups and 
help to fill the gaps in our evolutionary system. Such a form 
is Rhodochytrium, for it seems to occupy a transitional position 
between the protococcoid algae and some of the chytridiaceous 
fungi. It was described by its discoverer as an alga, but it has no 
chlorophyll and is strictly parasitic in its mode of life, being limited, 
moreover, to definite host species. Although entirely incapable of 
photosynthesis, it develops abundant starch. But the starch 
grains are apparently built up directly in the cytoplasm, for neither 
plastids nor pyrenoids have been found. This paradoxical com- 
bination of characters aroused in the writer a desire to investigate 
the details of its structure and to compare its cytology with that 
of Synchytrium, which has proved so peculiar. 
As is well known, Rhodochytrium has been found only in three 
widely separated regions. LLAGERHEIM observed it in many places 
in Ecuador on Spilanthis sp., and his material has been distributed 
in Wittrock and Norpstept’s Algae Exsiccatae as no. 1096. 
BARTHOLOMEW discovered it on Asclepias pumila about 20 miles 
from Stockton, Kansas, and distributed it as Fungi Columbiani 
no. 2166 (forma asclepiadis Farlow); and finally StTevENs and Hatt’ 
have found it on Ambrosia artemisiifolia in many places in North ~ 
Carolina, as reported by ATKINSON (3). BARTHOLOMEW has 
informed me that the plant is rare in Kansas and known to him 
from only one locality, but both in Ecuador and North Carolina 
‘Contribution from the Cryptogamic Laboratory of Harvard University, no. 
XV ; 
2 Mr. Hatt has also found it at Clemson, South Carolina. 
127] [Botanical Gazette, vol. 53 
