A DOMINANT MENDELIAN CHARACTER. 303 
that whilst some were completely sterile, others had some pollen, whilst an 
F! plant which was sterile x Bohemian Pearl gave a line composed of pollen- 
bearing plants and sterile plants in about equal numbers. 
Recessive “presence” breeds true.—“Flourball,” a well-known potato pos- 
sessing abundant pollen, has been raised by seed through three successive 
generations, and every member examined possessed pollen except in the 
instances noted later, and the great majority an abundance of pollen. In one 
family, 21 members, in another 16 were examined and all contained an 
abundance of pollen. 
The fertility of the female side is apparently entirely independent of that 
of the male. 
Quantity oF POoLLEN.—Certain empirical standards were taken for 
gauging the quantity of pollen present, and the following grades were 
differentiated :— 
Abundant; When the anther is full of pollen, and a touch of the needle 
liberates relatively large quantities of grains. 
Medium: When there is about half as much as is described as “ abundant,” 
but enough to allow a ready and sufficient supply for examination and fer- 
tilization. 
Small: When the pollen is present to the naked eye in the opened anther, 
but the help of a needle is needed to obtain sufficient for examination. 
Very few grains: When the anther is practically empty, or rather contains 
no free pollen, and the few grains that are obtained must be detached from 
the inner walls of the anther by the needle. This condition is equivalent to 
the absence of pollen, for such few grains as are obtained are all dead. 
QUALITY оғ POLLEN.—In examination, the shape and quality of the pollen 
as a whole, note has been made in each case of the relative quantities of oval, 
irregular, or round grains when dry, and the percentage of the grains which 
on addition of water swell up and become globular—i. е., to the quantity of 
pollen which is living. 
The method I use is to shed the pollen from the anther with the help of a 
needle on to a glass slide and then note its amount, and the relative quantities 
of elliptical, irregular, and round grains present. А cover-slip with a drop 
of water is then dropped on to the specimen and a fresh estimate made. 
These estimates are, in the nature of the method, nothing more than skilled 
guesses. The large number of estimations made, viz. over 300 in 1909 and 
400 in 1910, and the fact that the same pollen was often quite independently 
examined several times with remarkably similar results, allows the results to 
be used as a relatively sound basis of comparison, the personal equation being 
constant throughout the series. 
