YUZO HOSHINO 
267 
II. EXPERIMENTS WITH RICE 
The varieties of rice which can be grown in Sapporo, where the late frost 
ceases late in May and the early frost begins about the beginning of October, 
must be those which have extraordinary precocity. We have only a few 
varieties suitable for cultivation here. They are all local varieties specially 
bred. The difference of the ripening period amog these varieties is quite 
insignificant. They flower and ripen at about the same time. Even the ear- 
liest varieties in southern Japan do not ripen in the vicinity of Sapporo. 
In April 1907, the author procured a variety of rice, known by the name 
of Kuro-Bozu, through the kindness of Mr. S. Kato of Kinal Substation of 
the Imperial Agricultural Experiment Station near Osaka. We sowed the 
seeds in pots in a forcing house at the beginning of May, and after one month 
removed the pots into a glass house. But the shooting of its ears had delayed 
so much as to make it impossible for us to execute crossing between it and 
any of the local varieties. But we succeeded in the next year, 1908, in pro- 
ducing tlieir hybrids. 
Material Used and Experimental Methods. 
1. Late flowering parent: — Variety name; Kuro-Bozu (we shall denote 
it as K- p.) ; a variety of Oryza glittinosa ; awnless; tip of glumes black 
and with black striations on ridges of stalk. 
2. Early flowering parent : — Variety name Akage (A. P.) ; one of the 
local varieties of Oryza sativa ; with reddish brown awn; stalk without 
black striations. 
Our experiments were carried on in a glass house. We used zink pots 
24 cm. in diameter and 35 cm. in height. In the three years, — 1908, 1909 
and 1910, the pots were filled with the soil from a paddy field, but from 191 1 
on, we filled them with fine river sand, adding a suitable quantity of artificial 
fertilizers. At first, 5 plants per pot were grown, but afterwards, to plants 
per pot. The space in the glass house available for the present experiments 
