296 Beer, Development of tlie pollen grain and antlier of some Onagraceae. 
The microtome sections were particularly useful in sbowing 
tbe exact relations wbicb exist between tbe pollen grains and 
the otber cells of tbe antlier at the different periods of deve¬ 
lopment. 
I will give bere a few of tbe measurements wbicb I bave 
made of tbe pollen grain, its cell-cavity and its protoplast. Tbe 
stamens were examined directly after tbe removal of tbe flower 
buds from tbe plants wbicb were all strong bealtby individuals 
growing npon an open plot of ground. Tbe pollen grains were 
carefully teased ont of tbe antlier into a drop of tbe fluid wbicb 
was being studied and rapidly examined wliilst still uncovered. 
I. Tbe stamens from one bud were successively examined 
in tbe following Solutions (0. longiflora). 
1. 0,6% Na CI. 
Pollen grain = 42 y, 
„ cavity = 30 y, 
„ protoplast = 30 y. 
2. 0,75 % Na CI. 
Pollen grain = 46 y, 
„ cavity = 30 y, 
n protoplast = 30 y. 
3. 2 % Na CI. 
Tbis caused complete plasmolycis. 
Pollen grain = 40 y, 
„ cavity = 26 y, 
„ protoplast = 18 y. 
4. Egg-wbite, 
Pollen grain = 40 y, 
„ cavity = 26 y, 
„ protoplast = 26 y, 
Tbe results in tbis reagent were particularly uniform. 
5. Strong Flemmings solution. 
a) Pollen grain = 42 y, 
m cavity = 28 y, 
„ pro toplast = 26 y. 
b) Pollen grain = 42 y, 
„ cavity = 28 y, 
„ protoplast = 28 y. 
6. Strong cbrom acetic solution. 
Grave results similar to tbe Flemmings solution. 
7. Merkels solution. 
Pollen grain = 40 y, 
„ cavity = 30 y, 
„ protoplast = 30 y. 
Altbougb difficult to recognise at tbis stage Merkels solu¬ 
tion caused tbe protoplast to swell up and enlarge somewliat. 
