334 



Mr. J. J. Walker. 



[May 5, 



5. Acetic acid causes a cloudiness, which is increased by potassium 

 ferrocyanide. 



6. Copper sulphate and basic acetate of lead cause precipitates^ 

 soluble in excess ; mercuric chloride, a precipitate insoluble in excess. 



7. Copper sulphate and potash give a pink coloration (biuret 

 reaction). 



For the albumoses occurring in the vegetable kingdom I have 

 proposed the name phytalbumoses, as they differ in many respects from 

 the animal varieties. 



The phytalbumose in Abrus is closely allied to Kuhne and Chit- 

 tenden's deutero-albumose,* and identical with the a-phytalbumose 

 occurring in the papaw juice, f 



There are, therefore, two proteids in the seeds of Abrus precatorius,. 

 a vegetable paraglobulin and a-phytalbumose. In conjunction with 

 Dr. Wolfenden, I am now engaged in investigating the physiological 

 action of each of these proteids, and hope soon to publish the results. 

 For the present it will be sufficient to call to notice the close resem- 

 blance between the proteids of the papaw juice and those of jequirity, 

 since their physiological action appears to be in many respects similar. 



VIII. " On the Diameters of Plane Cubics. Preliminary Notice.' r 

 By J. J. Walker, F.R.S. Received April 21, 1887. 



I showed some time back (' London Math. Soc. Proc.,' vol. 10 r 

 pp. 184-5) that the Newtonian diameters of a plane cubic (u) 

 envelope a conic, called hereinafter its "centroid," the equation of 

 which, if in the system of co-ordinates chosen the line at infinity be 



tjx + rjy + Zz = 0, 



is generally 



Idy 2 dz 2 \dy dz) ) \dz dx dx dy dx 2 dy dz) 



The "centroid" has the same " criterion - function," but with 

 changed sign, as the cubic ; viz., it is equal to minus one-fourth of 

 the reciprocal of u, with the substitution of for a/fy ; i.e., if u be 

 written 



u = ax z + % 3 + z£ + • • • • + Gexyz, 

 the criterion-function is equal to 



-(b*c^+ . . . .)/4; 



* Kuhne and Chittenden, " Ueber Albumosen," c Zeitschr. fur Biologie,' 

 vol. 20. 



f " Nature of Papain, &c.," ' Journ. of Physiol.,' vol. 6, p. 344. 



