110 ISABURO NAGAT: 
The seed therefore, which belongs to the first type would be safely 
guarded against the action of toxic solutions when subjected to them. On 
the other hand, the seed of the second type, such as that of Leguminosae, 
would be less resistant, for there is a micropylar opening which conducts 
the toxic solution into the seed, even though the seed is wrapped up in 
9 
the “semi-permeable”’ septum, just as in the former type. 
It was Brown (1907, 1909) who first showed the presence of a “ semi- 
permeable ” septum in the seed covering of Hordeum vulgare, var. coerulescens, of 
Triticum, of Avena and of Secale. This fact is extended to Oryza (VALETON 
1907), Triticum (ScHROEDER 1911), Avena fatua (ATwoop 1914), Xanthium 
glabratum, Helianthus annuus, Vicia Faba, scarlet runner, lima bean, Alisma 
Plantago-aquatica, peach, apple (SHULL 1913), and sugar beet (TsEBBES 1912). 
The seed covering is reported to exclude the passage of the following : 
sodium fluoride, potassium chloride, sodium chloride, potassium nitrate, potas- 
sium carbonate, sodium carbonate, barium chloride, sodium sulphate, magne- 
sium sulphate, silver nitrate, cobalt chloride, seignette salt, cane sugar (wheat : 
ScHROEDER 1911), sulphuric acid, hydrochloric acid, copper sulphate, ferrous 
sulphate, potassium chromate, silver nitrate, potassium ferrocyanide, sodium - 
hydroxide (0.59), sodium chloride, sodium nitrate, potassium chloride, potas- 
sium nitrate, tartaric acid, cane sugar, dextrine, ammonium chloride, sodium 
acetate, (barley: Brown 1907, 1909), sodium chloride (wild oats: Arwoop 1914), 
sodium chloride, copper sulphate, potassium chromate, sodium thiosulphate, 
glycerol, sucrose, fructose, glucose, lactose, hydrochloric acid, tartaric acid, and 
citric acid (Xanthium : ScuuLL 1913); but to give entrance to the following, 
slowly or rapidly: sublimate, iodine, methyl and ethyl alcohol, ethyl ether 
acetone, acetonitril, chloroform, osmic acid (wheat: ScHROEDER 1911), ammonia, 
cadmium chloride, cadmium sulphate, glycocollic acid,* lactic acid,t glycerol, 
glycerine, urea, ethylene glycol, acetic acid, trichloracetie acid, ethyl alcohol, 
ethyl acetate, aldehyde, acetone, ethylic acetate (barley : Brown 1909), ammo- 
nium nitrate, silver nitrate, sodium nitrate, potassium nitrate, ferrous sulphate, 
potassium chloride, mercuric chloride, iodine in alcohols, ether, alkalies, 
sulphuric acid, nitric acid, acetic acid, and lactic acid (Xanthium: Suutt 1913). 
* Excluded until the lapse of 48 hours. 
T Excluded until the lapse of 2-9 hours. 
