THE AUSTRALIAN NATURALIST. 195 
grains when placed in water send out pseudo pollen tubes, 
either from one, two, or three corners, and do it almost 
as soon as they are immersed, 
Persooma has the three corners of the triangle turned 
to one side, so as to give the back of the grain a curved 
appearance, and yet one can still see the triangular out- 
line. Banksia shows a grain long and narrow, with only 
two corner caps, and may be a modification of the tri- 
angle—one corner may have been gradually cut off. Tfow- 
ever, this is merely conjecture. 
In the Myrtaceae the grains are again triangular, but 
with a marked difference (in most cases). from those of 
the Proteaceae. The Myrtaceous grain, when dry. has 
either a general smooth outline with no corner-caps show- 
ing, or else a sunken dark central triangle, which disap- 
pears slowly when the grains are placed in water, the 
central triangle being a fold in the wall of the grain, and 
it spreads out as the water is absorbed. Then can be 
seen three bands meeting in the centre of the pollen 
grain and one running out to each angle. This is seen in 
Eucalyptus, Melaleuca, Callistemon, Leptospermum, and 
many others. 
The corner-cap also difters from the proteaceous grain 
in having a button-like cap, and the edges of the extine 
(outer hard coat of the grain) curved inwards. 
Some of the species of Callistemon show a marked 
number of degenerated pollen grains present. 
In the Proteaceae, Stenocarpus, and Lomatia also 
show what appear to be degenerated grains, with a num- 
ber of parallel striations. giving the grain a beautiful 
banded appearance. 
SOME OBSERVATIONS ON SOLITARY WASPS 
AT ILAY, N.S.W. 
(By T. McCarthy.) 
During a recent visit to the Government Experiment 
Station at Hay nothing proved so interesting as the nest- 
making habits of the Thread-waisted Sand-digger, Ammo- 
