494 THE AMERICAN NATURALIST. | [Vor. XXXIX. 
heterotypic mitosis to his studies on the first division in the 
tetraspore mother-cell of Dictyota. But it can hardly be said 
that his account offers any material support to the theory. 
There is a clear synapsis stage preceding the mitosis in this form 
from which a spirem emerges as a beaded thread. This spirem 
then becomes split longitudinally and later the chromosomes are 
organized and show a longitudinal fission. The form of the 
chromosomes at metaphase of the first mitosis is heterotypic, a 
ring form being prevalent, and Williams concludes that it is 
developed by the bending and closing of the free ends of a 
loop. The events of synapsis are not clearly enough known to 
make possible a comparison with the accounts of Allen and 
Berghs. 
We are now ready to take up the latest conclusions of Stras- 
burger (:04b) which are closely associated with views expressed 
ina recent paper of Lotsy (:04). Lotsy givesa clear state- 
ment, illustrated with many diagrams of the various ways in 
which sporophytic chromosomes may be conceived to unite in 
pairs previous to the first mitosis in the spore mother-cell and 
the manner in which the resultant bivalent chromosomes may be 
divided and distributed by the two mitoses of sporogenesis. 
Lotsy makes parallel comparisons between sporogenesis in plants 
and gametogenesis in animals and proposes the term “Gonoto- 
konten" (* Nachkommenbildner") for the mother-cells which 
inaugurate reduction phenomena. The paper presents no new 
observations but discusses the problems of reduction in their 
broad aspects. An excellent summary is given by Koenicke 
(: 04) | 
Strasburger's (: 04b) most recent paper, * Ueber Reduktionstei- 
lung," is based chiefly on studies of Galtonia and Tradescantia 
and presents an entire change of view from his conclusions of 
1900. Galtonia seems to bea very favorable form for study since 
the gametophyte number of chromosomes is only six and the 
structures are exceptionally clearly differentiated in the spore 
mother-cells, which Strasburger calls ** Gonotokonten” after 
Lotsy. A single spirem is reported to split longitudinally but 
the two daughter threads remain close together. The spirem 
then shortens and thickens and becomes distributed in heavy 
