296 Beer, Development of the pollen graiii niid nniher of some Onagraceae. 



The microtome sections were particularly useful in showing 

 the exact relations \vliich exist between the pollen grains and 

 the other cells of the mitlier at the diffcrent periods of deve- 

 lopmcnt. 



I Avill give hero a fcw of thu iiieasurements \vlueli 1 have 

 made of the pollen grain, its cell-cavity and its protoplast. The 

 stamens were examined dh'ectly after the removal of the flower 

 buds from the plants whicli were all strong healthy individuals 

 growing npon an open plot of ground. The pollen grains were 

 Ciu-efuUy teasod out of the anther inlu a drop of the liuid which 

 was being studied and rapidly examined whilst still uncovered. 



I. The stamens from one bud were successively examined 

 in the following Solutions [0. hugiflora). 



1. 0,6% NaCl. 



Pollen grain = 42 //, 



„ cavity = 30 //, 

 „ protoplast = 80 //. 



2. 0,75 o/o Na Gl. 



Pollen grain = 46 ,a, 



„ cavity = 30 fl^ 

 „ protoj)last = 30 //. 



3. 2% Na Gl 



This caused complete plasmolycis. 

 Pollen grain = 40 //, 



„ cavity = 26 //, 

 „ protoijlast =^ 18 ft. 



4. Egg-white, 



Pollen grain = 40 //, 



„ cavity = 26 //, 

 „ protoplast = 26 //, 



The results in this reagent w^ere particularly uniform. 



5. Strong Flemmings Solution. 



a) Pollen grain = 42 //, 



;, cavity = 28 //, 

 ,, protoplast = 26 /j. 



b) Pollen grain = 42 //, 



„ cavity = 28 //, 

 „ protoplast = 28 /j. 



6. Strong chrom acetic Solution. 



Gave results similar to the Flemmings Solution. 



7. Merkels Solution. 



Pollen grain = 40 //, 



„ cavity = 30 //, 

 „ protoplast = 30 //. 



Although difficult to recognise at this stage Merkels Solu- 

 tion caused the protoplast to swell up and enlarge somewhat. 



