Macrosporium parasiticum , Thiim . 3 
cipal transverse septa and a longitudinal one, usually with 
further subdivisions by oblique, transverse or longitudinal 
partitions, making them into five-, six-, or at times seven- 
septate muriform spores. Their wall was slightly constricted 
at the principal septa. It was covered to a greater or less 
extent all over the surface with very minute projections. This 
roughness of the spore was quite characteristic ; though very 
rarely one might meet with a spore which looked perfectly 
smooth. The spore measured 33-43 by 18-23 m.mm., and the 
average size was about 37 by 21 m.mm. (Figs. 1 f and 2). 
On the Bermuda specimens, besides the Macrosporium - 
spores, a large number of young perithecia were observed. 
Among numerous sections made on different portions of the 
leaves, I obtained only once the unripened resting-spores of 
Peronospora Schleideniana. The Macrosporium- spores were 
abundantly seen around the perithecia, with which it was 
proved that they have organic connection. The perithecia were 
still too young for the satisfactory determination of species. 
With regard to our Macrosporium , it has been clearly proved 
to be identical with Macrosporium parasiticum , Thiimen, by 
careful comparison with authentic specimens. So far as I 
am aware, nothing has been published on the life-history of 
Thumen’s species 1 . With a view to determine it as completely 
as possible, the following cultures were conducted. 
The different culture-methods were followed according to 
the nature of the results to be attained. For observing the 
germination of the spores under the microscope, the formation 
of the perithecia, and the rest of the earlier stages of the de- 
velopment of the plant, the Van Tieghem cell was employed. 
For the study of its further development, the Erlenmeyer 
flasks proved to be most useful. For nutrient fluids, thin 
decoctions of onion, of date, of grape, and of horse-dung were 
used. The onion and date gave the most satisfactoryresults. 
Both fluids and apparatus had been carefully sterilised before 
any sowing was done. 
Up to the end of March, fifteen cultures in the Van Tieghem 
1 [See Appendix to this paper. Ed.] 
B 2 
