2 BOTANICAL GAZETTE [JANUARY 
September 1911. Material for the study of Liriodendron was 
obtained at Homewood, the new site of the Johns Hopkins Uni- 
versity, and that for Magnolia in a swampy region at Glen Burnie, 
Maryland, a typical habitat for the so-called swamp magnolia. 
Most satisfactory results were obtained by using a chromacetic solu- 
tion for fixing, although acetic alcohol worked wellalso. The prin- 
cipal stains used for sporogenous tissues and young embryo sacs 
were iron-hematoxylin and orange G; and for older sacs safranin 
and Delafield’s hematoxylin, or for embryos hematoxylin alone. 
The writer is greatly indebted to Professor DUNCAN S. JOHNSON, 
and desires to express thanks for many suggestions and much 
helpful criticism during the progress of the work. 
As the course of development is very similar in Magnolia and 
Liriodendron, in the following description attention will be directed 
mainly to the former, differences between the two species being 
pointed out where they occur. 
The stamens of Magnolia and Liriodendron have elongated 
anthers on short filaments, the connectives extending beyond the 
anthers. The anthers contain four locules, with walls of 3 or 4 
layers of cells, and dehisce longitudinally. In Magnolia the spo- 
rogenous tissue in the stamens is already differentiated early in 
December (fig. 15), and in Liriodendron early in January. Little 
change occurs in this tissue until March, when the sporogenous cells 
enlarge considerably and divide. The nuclei of the microspore 
mother cells are found in synapsis from April 20 to May 1 (fig. 16). 
The first mitosis in both species usually occurs during the first week 
in May (fig. 2), and tetrads are developed by the simultaneous 
method about May 1o (fig. 18). 
After the first and second mitosis of the nuclei of the micro- 
spore mother cells the number of chromosomes is 19 (figs. 3 and 19). 
The actual number in the microspore mother cells, or in the vegeta- 
tive tissues, was not determined, but is much greater than 19; 
therefore, as the usual heterotypic division occurs in the microspore 
mother cells, and after this division a smaller number of chro- 
mosomes than before is present, there can be little doubt that in 
microspore formation reduction takes place, and that the « and 
2x generations are characterized respectively by 19 and 38 chro- 
