HYBRIDS 131 



hollow end of the straw may be plugged with a bit 

 of cotton so that the shovel end which protrudes 

 will carry only a few grains at a time to be dumped 

 on the female flower. The bag is again tied over 

 the branch and allowed to remain for several days 

 longer before being finally removed. In order to 

 mark any particular limb it is well to fasten a wooden 

 tag with a copper wire about the branch. If twine 

 is used red squirrels are likely to cut it as a matter 

 of pure mischief in all probability. I would not pre- 

 tend to follow the ideas of the red squirrel further 

 than to say that it does many things in the spirit in 

 which I did them as a boy. 



Pollen is secured by shaking the male flowers when 

 in full bloom on a sheet of paper very gently and 

 then rolling the collected pollen into a paper box, 

 where it may be kept for some days. The paper 

 box containing the pollen should be kept in a cool 

 place or in cold storage and there should be a con- 

 siderable degree of moisture in the air where the box 

 is kept, although the pollen should not be allowed 

 to become really moist. If it is allowed to dry it 

 soon loses viability and if kept too moist it is quickly 

 attacked by fungi and bacteria. Some kinds of pol- 

 len remain potent for a few days only while others 

 retain viability for a couple of weeks. 



Where the trees which are to 1 furnish pollen have 

 a blossoming time far from that of the trees which 

 are to receive pollen I have secured pollen from the 

 northern and southern limits of the range of the 

 species desired. Thus, for experimental work in 



