294 THE AMERICAN MONTHLY [Nov 
tributes to rapid growth. A banana petiole cut off at 
the base of the leaf and 42 ¢ m. farther down was found 
to displace 239 c.'c. of water and to weigh 57.5 grams. 
The net specific gravity was 1.085. Hence there were 
only 53 c. c. of vegetable matter and sap to 186 c. c. of 
air. The weight after drying was 5.04 grams. So we 
have about 1 measure of solid matter to 10 of water and 
186 of air. This petiole sustained a leaf weighing 192 
grams. 
But for lightness the swelled petiole of the Hichornia 
must bear the palm. The one shown in fig. 9, of quarter 
size, measured 50c.c.and weighed4.4grams. Air-dried, it 
weighed 0.334 grams. So 11-12 of the bulk was air, and - 
1-13 of the weight was solid matter. 
Air-spaces with diaphragms seem to have some con- 
nection with the parallel veining of the leaves. In the 
leaves of Iris versicolor the partitions are not perforated. 
I have n&8t yet found diaphragms in any dicotyledonous 
plant. There are four large air-ways in Nymphea odo- 
rata and many more in Nuphar advena, but here the re- 
markable, stout, many pointed, distinct cells may act like 
skewers to keep the parts in place and yet do not inter- 
fere with the flexibility. In Nelumbo lutea the same of- 
fice appears to be performed by adherent clumps of cal- 
cium oxalate crystals which are purposely distributed 
along the inner walls of the four large air-passages. 
H. S. Newcomb M. College, New Orleans, Oct. 31, 1901. 
Catalogues of Microscopes, etc. can be had from 
R. & J. Beck, Ltd., 68 Cornhill, London. 
Negretti & Zambra, 38 Holborn Viaduct, London, E. OC. 
W. Wilson, 1 Belmont St., Chalk Farm, London, N. W. 
Clarkson & Co. 28 Bartlett’s Bdgs., Holborn Circus, Lon- 
don, E. C. 
W. Watson & Sons, 313 High Holborn, London, W. OC. 
England. 
