40 LOUIS OTTO KUNKEL 
gathered in Van Cortlandt Park, New York City. I have, however, 
also germinated spores that were sent to me from Urbana, Illinois; 
Columbia, Missouri, and Madison, Wisconsin. I find that they all 
produce promycelia. 
Spores having promycelia in various stages of development were 
floated from tap-water cultures on to glass slides. They were attached 
to the slides by means of egg albumen, fixed, hardened in alcohol and 
stained with the triple stain. The ripe ungerminated aecidiospores 
seem difficult to fix and it was necessary to make many preparations 
in order to secure a sufficient number of slides that show the nuclei 
clearly defined and well stained. This difficulty in the fixation of the 
ungerminated spores- is probably due to the slowness with which the 
fixative penetrates their dry cell walls. As soon as this wall is pene- 
trated by the promycelial tube, the contents of the spore become easy 
to fix and readily stain. 
In agreement with the observations of Olive (16) and Kurssanow 
(11), I find that the normal aecidiospores are binucleate. A study of 
stained sections through the caeoma, however, shows that, as Olive 
and Kurssanow have already observed, occasionally there are rows 
of spores, each of which contain more than two nuclei. Such spores 
are larger than the binucleate spores and their size is roughly propor- 
tional to the number of nuclei which they contain, thus maintaining 
nucleo-cytoplasmic ratio. Kurssanow found that these spores arise 
through a fusion of more than two cells in the caeoma. Two of these 
abnormal spores, one containing three nuclei and the other containing 
four nuclei, are shown in figures I and 2. A normal binucleate spore is 
shown in figure 3. 
A study of the binucleate spores during germination shows that 
they become uninucleate previous to the production of promycelia. 
Preparations made from cultures that were fifteen hours old show a 
large number of uninucleate spores. In some of these preparations 
more than ninety per cent, of the spores contain only one nucleus, thus 
demonstrating that during the early stages of germination the bi- 
nucleate spores become uninucleate. This observation strongly sug- 
gests that a nuclear fusion takes place. A large number of spores have 
been studied with the hope that the actual stages in such fusions could 
be demonstrated. The nuclei are clearly defined and can frequently 
be observed to lie close together and flattened against each other, but 
the actual breaking down of the membranes and the union of the 
