No. 387.] PLANT MORPHOLOGY AND PHYSIOLOGY. 213 
abundant along the margin of mesas, and along hills bearing a certain 
topographic relation to adjoining valleys. The most striking example 
of this fact is to be seen along the mile-deep cañon of the Colorado 
river. Here the heated air rising from the river bed, under the rays 
of a sub-tropical sun, loses 20° F. of heat in its vertical ascent of 
over a kilometer. As a consequence it pours over the rim of the 
mesa heavily laden with moisture, and the Razoumofskya is quite 
abundant in a belt a KONPE 3 in width running parallel to the rim, 
while it is greater distances from the cañon. 
T 
Di Erre 
ProF. Conway Mac MILLAN: Notes on the Reproduction and Devel- 
opment of Nereocystis. — The author described the great bladder kelp, 
N. Liitkeana, which is abundant in the swift tide-water channels of 
Puget sound, and which frequently reaches the enormous length of 
80 to 100 meters. He has studied several hundred specimens (col- 
lected by Miss Josephine Tilden) with special reference to structure 
and early stages of growth. He exhibited a plant less than 1 milli- 
meter long, and also one about 10 meterslong. The latter consisted 
of a hollow green stem several centimeters in diameter at the base 
where it was anchored to the mud or rocks by a mat of large branched 
thizoids, about 2 decimeters broad. This green stem gradually en- 
larged, until, at a distance of about 3 meters from the rhizoids, 
it very gradually expanded into a bulb 8 or 10 centimeters in diam- 
eter. This was crowned by the broad, thin, and very long, floating 
green laminæ. The figure given in Die Natirlichen Pfhlanzenfamilien 
is nota very good one. At low tide the sea is dotted with these 
floating bulbs, and the plants are so strong, in mass, that fishing 
boats may be anchored to them, while smaller boats are sometimes 
capsized by them. As is well known, the Aleuts formerly used the 
flexible hollow stem to siphon water from their boats. 
Spores in sporangia are the only known reproductive bodies. 
~ Calosities occur on old plants. Sieve tubes are present. They are 
pulled out by the elongation of the stem, and are undoubtedly con- 
verted into gelatin. They are morphologically different from trumpet 
hyphæ. No evidence of protoplasmic connections was obtained. 
The cryptostomata disappear on old plants. The cleft in the lamina 
arises not as a tear, but is started by the deliquescence of a single 
row of cortex cells just below the epidermis. As the result of this 
continued deliquescence an ever deepening fold arises which finally 
cuts the lamina into two. Many slides, specimens, photographs, 
and drawings were exhibited. 
