CYLINDROSPORIUM ON STONE FRUITS 
18 hours there was an almond odor in the tubes containing the un- 
boiled extract and by the end of 8 hours this odor was very strong. 
At this time they were tested for reducing sugar and for HCN. Both 
were present in the tubes containing the unboiled extract while the 
checks gave no trace of HCN and only a slight trace of reducing sugar. 
The other cultures were crushed in a mortar, extracted with 30 per 
cent alcohol, filtered, and the filtrate treated in the same way that 
the liquid from the other tubes had been treated. In every case 
emulsin was found to be present in themnboiled extract. 
For comparison with the behavior of Cylindrosporium and its 
hosts, a Septoria found on leaves of P. pennsylvanica was studied. 
In this case the mycelium passes directly through the host cells and 
kills the host tissue before fruit bodies are formed. The spots drop 
out less frequently than Cylindrosporium spots on the same species. 
Where they do drop out however there is a separation layer formed in 
the living tissue just outside the dead tissue. A similar separation 
layer was also found in leaves of P. americana affected with Cercospora. 
(From herbarium material distributed as Cylindrosporium padi Karst. 
in Grifiith's "West American Fungi" 75a.) 
Frank (11) also found that such a callus layer is formed around 
spots infected by Gnomonia erythrostoma Pers., and Duggar (8) 
noticed its formation in leaves of Prunus in which "shot hole" was 
produced by poisonous compounds. 
Development of the Perfect Stage^ 
The perfect or ascigerous stage of the fungus on P. avium was 
found in the spring of 191 1 and its development was studied more 
closely during the winter and spring of 191 2. From the knowledge 
thus gained it has been comparatively easy to find and follow the 
development of the perfect stage on the other hosts under observation, 
especially since trees whose leaves were infected with Cylindrosporium 
were located during last summer (1912). It has been found on all the 
hosts under observation except P. spinosa, of which only a few leaves 
were found infected with the conidial stage last summer. 
There is considerable variation in the perfect stages found on the 
brief description of the structure and development of the perfect stage of 
Cylindrosporium on P. avium was given in a previous note (16); but since many 
points of interest could not be included in a brief note, the entire development will 
be given in more detail here. 
