Sands—Spore Formation in Microspha&ra Alni. 737 
strongly developed, and later are active in the formation of the 
spores. 
Harper has recently extended his studies on the mildews to 
Phyllactinia (13) and finds there that the development of the 
ascogonium from a fertilized egg, the budding out of the ascog- 
enous hyphae, and the origin of the asci are essentially the 
same as in Frysiphe and Sphaerotheca (11, 10). 
In Phyllactinia , the nuclei in every stage throughout the 
life history of the fungus show central bodies, and furthermore 
the chromatin is always oriented on the center. The center is 
described as a disc-shaped body lying on the periphery of the 
nucleus, or in a flight depression of the nuclear membrane. 
The chromatin is always attached to the center, hut its exact 
arrangement cannot be made out in the vegetative hyphae and 
young ascogone as clearly as in the larger nuclei of the ascog- 
enous hyphae and asci, where the number of strands which 
radiate from the center into the nuclear cavity can be counted. 
In the fusing nuclei of the asous, the centers fuse into one, 
and the eight chromatin strands of each nucleus combine in 
such a way as to form exactly eight strands in the fusion nu¬ 
cleus. 
The nuclear fusion is followed immediately by synapsis, in 
which the chromatin is drawn up in a mass against the central 
body. The chromatin emerges from the synaptic condition in 
the form of a spirern with eight distinct strands attached to 
the central body,. Each strand of the spirern forms one of the 
eight chromosomes, which are still connected with the center 
by means of the linin threads. 
The central body divides and the two daughter centers in 
migrating apart to form the spindle poles separate the fibers 
which connect the chromosomes with the center, so that each 
chromosome is seen to be attached to both centers. This con¬ 
tinuous connection of the central body with the chromatin 
strands, and later with the chromosomes themselves, is fur¬ 
ther used as evidence that the chromosomes are permanent 
structures of the nucleus. 
Here for the first time the fact has been established that 
there is a permanent connection between the center and chro- 
