THE PROBABLE NON-VALIDITY OF CERTAIN GENERA 325 
Historical. — While working on a branch and trunk disease of cocoa, 
Jonge and Dorst (13) in 1909, carefully studied the causative fungus 
Diplodia cacaoicola Henn. They noticed that although the organism 
seemingly belonged to the genus Diplodia, under certain cultural 
conditions its pycnidia would be hairy and possess paraphyses inter- 
mingled with the basidia of the sporules. Different workers have 
actually placed this fungus under the different genera here mentioned, 
as will be seen later under its synonymy. Jonge and Dorst (13) 
further found that if the diseased specimens of cocoa were placed in 
moist surroundings, hair developed on the pycnidia, whereas dryness 
tended to suppress them. From these studies they concluded that 
the genera Chaetodiplodia and Lasiodiplodia are not valid. 
In the same year (1909) Griffon and Maublanc (10), while working 
on a similar cocoa disease, came to conclusions similar to those of 
Jonge and Dorst (13). Griffon and Maublanc placed the fungus 
Diplodia cacaoicola Henn. in the genus Lasiodiplodia and named it 
L. theobromae (Patt.) Griff. & Maubl. Bancroft (2) (1911) in his 
work on a para rubber and cocoa disease, found that the causative 
fungus, Diplodia cacaoicola Henn. was so variable that it could easily 
be placed in any one of the genera Botryodiplodia, Macrophoma, and 
Lasiodiplodia. Bancroft, however, found the ascigerous stage of the 
fungus, which he named Thyridaria tarda Banc. That the presence 
or absence of paraphyses in pycnidia or perithecia have no taxonomic 
value has also been indicated by Shear and Wood (22). "Their 
presence or absence (paraphyses) does not seem to be sufficiently 
constant to be of much taxonomic value." 
Present work. — As previously stated these investigations are an out- 
growth of studies on Lasiodiplodia tubericola E.&E., the cause of a sweet 
potato disease. In order to determine the relationship of the genus 
Lasiodiplodia to the genera Diplodia, Diplodiella, Chaetodiplodia, and 
Botryodiplodia, the following experiments were carried out. A large 
number of apparently healthy sweet potato roots were divided into 
five lots. These were carefully washed in tap water, then disinfected 
by being plunged in a 5 percent formaldehyde solution for ten minutes. 
Each lot was then carefully dried with clean cheese cloth, placed in flat 
moist chambers, and kept one week in the laboratory. Any root 
which showed signs of decay because of internal infection was dis- 
carded; infection in such cases was chiefly soft rot, Rhizopus nigricans 
Ehr. At the end of the week ten roots were finally placed in each 
