312 BOTANICAL GAZETTE [octoBER — 
here published, and the text is supplemented by twenty-seven full-page illustra- 
tions.—J. M. GREENMAN. 
Handbook of deciduous trees.—The ninth part'® of ScHNEIDER’s Handbook 
(the fourth section of the second volume) has followed the preceding one?" with 
great promptness. As already noted. it presents descriptions of the species of 
angiospermous trees, native or under cultivation in central Europe, and is illus- 
trated freely. The present part begins with Tilia and ends with Rhododendron. 
—j. M. C. ; 
NOTES FOR STUDENTS 
Morphology of Tumboa:—Three years ago PEARSON published? the results 
of his investigation of Tumboa (Welwitschia) from material obtained in one day’s - 
collecting. A second expedition to Damaraland was made possible and material 
was collected during January and February of 1907, the results of the investiga 
tion of which are now published.73 The additional stages thus secured have 
put our knowledge of this most interesting plant upon a fairly substantial basis, 
and Pearson is to be thanked for his persistent enthusiasm in securing this 
difficult material. An outline of what seem to be the most significant new results 
is as follows: 
The staminate and ovulate strobili are often produced in great profusion 
and their occurrence below the single pair of leaves is frequent. Pollination is 
mainly effected by a hemipterous insect (Odontopus), the pollen being received by 
a nectar drop on the top of the projecting micropylar tube. The pollen grains 
frequently germinate in the micropyle at some distance from the tip of the nucellus, 
pollination. The generative cell passes into the tube, where its nucleus divides, 
the binucleate cell either remaining undivided or forming two male cells. The 
tube nucleus begins to break down before fertilization and eventually disappears. 
The most critical and puzzling structure of Tumboa, however, is the embryo 
sac. Megaspores and embryo sacs are often present in the pith region of the 
axis of the ovulate strobilus, so that the cauline origin of the ovule is clear. A 
single megaspore mother cell is organized and a single megaspore functions. The 
female gametophyte begins with free nuclear division and no vacuolation, and 
successive simultaneous divisions occur until there are approximately 1024 free 
and crowded nuclei. Elongation of the sac then occurs, chiefly in its micropylar 
+¢ SCHNEIDER, C. K., Illustriertes Handbuch der Laubholzkunde. Neunte Liefer- 
— (vierte Lieferung des zweiten Bandes). Imp. 8vo. pp. 367-496. figs. 249-. 328. 
ustav Fischer. tg09. M 4. 
*« Bor. GAZETTE 472415. 1909. 
12 Pearson, H. H. W., Some observations on Welwitschia mirabilis escapee: 
Phil. Trans. Roy. Soc. London B 198:26s-304. pls. 18-22. 1906. Review in Bot. 
GAZETTE 42:67. 1906. 
13 __—, Further observations on Welwitschia. Phil, Trans. Roy. Soc. London 
B 200:331~-402. pls. 22-30. 1909. 
