12 



BULLETIN 542, U. S. DEPARTMENT OF AGRICULTURE. 



have ceased, as no further changes were produced by leaving the 

 cultures longer. (Fig. 1.) 



RESULTS OF GERMINATION TESTS. 



By the method described, cultures were made of pollen from all 

 the varieties which it was possible to obtain near Miami, including 



Fig. 1.— Pollen grains of seedling mango of No. 11 type after 24 hours in a 25 per cent sugar solution, 

 showing the development of the tubes. Greatly magnified. 



several seedlings. The percentage of germination was in no case 

 high and did not indicate that the superior productiveness of some 

 varieties was due to the greater viability of the pollen. It was sig- 

 nificant, in fact, that the best germination was obtained with a vari- 

 ety which is markedly unproductive, the Mullgoa. In the seedling 

 No. 11 race, also, a comparatively good germination was obtained 

 in several instances, while the Mulgoba variety was one of the most 



