CHuatic conditions and distribution and tlie San Jose Scale. I9 



and tbey mike an excursion toward Mt. Gaiite about 14 miles Iroin Morioka 

 city. On the liekls and plains the wikl paar wa^ generally distributed, giving 

 a good chan3e for the investigation ; and at the same tim'^. the writer paid 

 careful attention to the following plants : 



Pirus toringo Sieb. AVild pear. 



{Ztivii, Hinielaido, Mifsuhalaido, YatsmnoDio,) 

 Pirus sambucifolia Ch and Schl. 



(M iyam a lamado) 

 I'irns ancuparia Gaertn. 



{Naiialiamado) 

 Pirus sinensis Lindl. 



(Na^hi) 

 Eosa sp. • 



(Ibara) 

 Acer sp. 



(Kacde) 



The result was that the writer could not find the scile on any of the 

 plants above mentioned ; so he concluded at once that the scale on the wild 

 pear trees in Morioka city, which he founcl three years ago, must have come 

 from other hosts in the yard at that time. 



IX. Climatic conditions and distribution of the San Jose Scale. 



It is well known fact that certain kinds of animals and plants have a 

 definite limited range of occurrence or distribution; naturalists call such limits 

 life zone, within which particular animals or plants thrive, and outside of 

 which they fail to establish themselves. But up to a certain degree this 

 natural law has been disturbed artificially by the international trade ; if a 

 plant is transferred into a climate strange to its original home, the animals 

 fed upon it would also survive well ; and they would find their food even 

 under a great change of climate. Under considerably great change of the 

 conditions, however, they would often be completely destroyel. 



