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VOLUME XLIX NUMBER I 
BOTANICAL _CGFAZETTE 
JANUARY 19g10 
CHROMOSOMES IN OSMUNDA 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 132 
SHIGEO YAMANOUCHI 
(WITH PLATE 1) 
This paper presents the results of a study of the behavior of 
chromosomes during both homotypic and heterotypic mitoses in 
Osmunda cinnamomea L. 
The material was collected in the vicinity of Chicago, Illinois, 
in the late summer of 1906 and the spring of 1908. The study was 
made on both living and fixed material. Fixation was most satis- 
factory in Flemming’s weak solution containing osmic acid. The 
chromosome conditions were studied not only in vegetative mitosis 
in sporophytes, and in sporogenesis, but also in germinating spores 
and in mature prothallia. This paper, however, will be limited to 
a brief account of chromosomes in the sporophyte. 
Papers dealing with the cytology of Osmunca have been published 
by Humparey (7), STRASBURGER (15), SMITH (14), FARMER and 
Moore (2), and by GrécorreE (4). These authors have all chosen 
Osmunda regalis. HumpHrey and Sire devoted their attention 
chiefly .to the achromatic substance; STRASBURGER studied sporo- 
genesis and the number of chromosomes; FARMER and Moore 
claimed that the bivalent chromosomes arise by a folding of the 
spirem; and GrEcorrRE studied chiefly the structure of the double 
spirem of synapsis, which he found to originate by the association 
of two independent chromatin threads. Gr&corre’s account is 
in accord with the present study of Osmunda cinnamomea. 
The cytological investigation was carried on in the Hull Botanical 
Laboratory of the University of oe under the direction of 
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