138 



A 



5 

 o 



V 



■> PLASTIC UNIT 



5IDE VIDN OF LHB HOLOLR 

 MADE UP OF 2 INDEPENDENT 

 PIECES OF STEEL MOUNTED 

 AND SCREHED TOGETHER 

 (IMITH A nEY). 



y/EW FROM ABOVE OF THE 

 LHB HOLDER IVITH MOUN- 

 TED PLASTIC UNIT. 



m m. 



Fig. 256. LKB object-holder with plastic unit mounted (1:1). 



When estimating the size of the pyramid, the following three factors 

 should be taken into account: 1. the desired thickness of the sections (the 

 thicker the sections the larger, and especially the higher, the pyramid must 

 be); 2. the size of the pollen grains (the size of the pyramid should be in- 

 creased or decreased in proportion to the size of the pollen grains; if large 

 pollen grains or spores — diameter about 80 /^ or more — are to be cut 

 sometimes as few as 1-3 pollen grains will be sufficient, cf. Fig. 258); 

 3. the concentration of the pollen grains (cf. Fig. 259; if the concentration 



> LHB STEEL HOLDER 



Fig. 257. Preliminary cutting of the plastic unit. 



