760 Summary of Agricultural Experiments. [Dec, 



extract were tried, but failed to give the seed a noticeable taste. Seed 

 dressed with powdered aloes, however, in the proportion of 100 parts 

 by weight of seed moistened with 8 parts of water containing o'6 part of 

 powdered aloes, acquired a very bitter taste. The germinating power 

 of the seed did not appear to suffer. 



Tobacco extract, Fichtenin and fusel oil proved useless for giving a 

 noxious smell to the seed, but a 3 per cent, creolin solution in 8 parts of 

 water to 100 parts of seed was satisfactory. 



Four experiments were carried out as follows 



(a) 200 grammes each of seed dressed with Prussian blue, red, 

 and aniline green, and of undressed seed, were placed in a large 

 cage containing ten rooks, and the feeding boxes were arranged 

 in such a way that the birds had to pass the coloured seed to 

 get at the undressed seed. After a short time it was found that 

 the amounts eaten were respectively 3 grammes of seed dressed 

 with Prussian blue, 35 grammes of that treated with red colour, 

 8 grammes of that treated with green, and 68 grammes of 

 undressed seed. 



(b) Two rooks were placed in a large cage, the floor of which 

 was divided into n beds. They were fed on corn, etc. for about 

 nine days, to allow them to become accustomed to their sur- 

 roundings, after which the beds were sown in rows with seed 

 both unprepared and prepared in all the above ways. The 

 experiment lasted four days, and it appeared that the seeds 

 dressed with Prussian blue, creolin and aloes were most shunned 

 by the birds, though, it was difficult to determine the point 

 exactly. 



(c) In the third experiment, eight rooks were used and 100 

 grammes each of seed undressed and dressed with Prussian blue, 

 red and green were thoroughly mixed and placed in a feeding 

 box so constructed that seeds dropped by the birds would fall into 

 the box again. After 24 hours it was found that 51 grammes of 

 blue, 57 grammes of red, 55 grammes of green and 94 grammes 

 of undressed corn had been eaten. 



(d) The fourth experiment was conducted under the same 

 conditions as the second, but the seeds were allowed to germinate 

 with a view to ascertain what proportion of plants survived. 

 Three beds were sown on the 20th June with undressed seed 

 and with seed dressed with Prussian blue and powdered aloes 

 respectively. Two rooks were kept in the cage for 48 hours. 

 After 9 days it was found that the bed sown with unprepared seed 

 contained 247 plants, while the seed dressed with Prussian blue 

 and powdered aloes had produced 796 plants and '760 plants 

 respectively. 



Dressing with a blue colour appeared, on the whole, to be most effec- 

 tive, while green and the creolin dressed seed were also avoided. Red 

 seemed of little value, but the aloe dressing was very satisfactory. The 

 cost of the preparations was comparative!}^ trifling. 



How far the results obtained in these experiments are applicable 

 to ordinary practice is a matter for further investigation, but they appear 

 to show that rooks in their search for food are influenced by colour, 

 smell and taste. 



