8 BULLETIN 1250, U. S. DEPARTMENT OF AGRICULTURE. 
That haif-shp melons are extremely variable is shown in column — 
6, Table 4, where the indexes vary from 47 to 61. When these 
melons were analyzed the half slips with high indexes were well 
flavored, while those with low indexes were of doubtful or unsatis- 
factory quality. The half-slip group, then, contains both mature 
and-immature melons. A fairly satisfactory commercial separation 
of the half-slip group can be made on external appearance alone 
(Table 10). 
Objection may be made to the use of the refractive index as an 
indication of maturity from the fact that Table 4 shows that field- 
ripe melons have a lower index than full-slip melons. Additional 
_evidence in Tables 2 and 3 proves that field-ripe melons have a lower 
sucrose content, specific gravity, and refractive index than full slips. 
The reason for this may be twofold. First, after reaching maturity, 
the fruit automatically starts to detach itself from the vine, and food 
materials, the further supply of which is restricted, especially the 
sugars, are used up in the rapid respiration that takes place at the high 
field temperature. Second, for reasons not understood, the normal 
development of the fruit may be interrupted and a yellow color pre- 
maturely attained (field-ripe melon 18, Table 4). 
Melons that become yellow in the field are often of unsatisfactory 
quality, and they are never selected when melons of dependable 
edibility are desired. 
Great confidence may be placed in the correlation between refrac- 
tive index and development. An immersion refractometer furnishes 
the most satisfactory means of placing a numerical value upon the 
extent to which melons have developed. The determination can be 
quickly made on small quantities of juice and small differences can 
be accurately measured. 
STARCH IN SEEDS. 
Soon after the analytical work was begun it was noted that extracts 
of seeds from immature melons gave a strong blue color when tested 
for starch by the iodine method, while those of seeds from mature 
melons contained no starch or only traces of it. The results of the 
starch tests in 1916 and 1917 are shown in Table 5. 
TaBLE 5.—Starch in seeds as an indication of maturity. 
BRAWLEY (1916) (MELONS NOT STORED). 
Stage of development.} Stage of development. 







| 
| res 
Field . : | Im- || Field : : Im- 
ripe, | Fullslip. Ene oe ike. | Fullslip.| Halfslip.| ature. 
a ee i =e 
Se ee — A i | A | A A 
N A pi is ees | \ r 
tee Wee Ses. Carers 
2 aa SEA See Ff A A 
A jag Sel Sel ES ek i} A in) 
\ \ ae Se ihe Se T | 
| I 


1A, starch absent; T, trace of starch; P, starch present. 
