INFLUENCK OF CLIMATE ON ANIMAL DISEASE. 501 



(_)ne of these is the observation made in rej^ard to the toxicity 

 of the SlViccio species, and in this case, whilst it was shown by 

 Robertson and Chase that a form ()f Hver cirrhosis could be 

 produced by feeding' animals with the plants obtained in the Cape 

 Province, yet the same s])ecies of ])lants collected at a later date, 

 and in Xatal, did not ])rodnce a similar affection when fed to 

 animals in experiments made by Webb. '!'he other observation 

 is one of the writer's made in connection with the toxicity of 

 Cotylcdo)! orblculata when fed to fowls. In this case it was noted 

 that whilst the ])lant collected near Pretoria was toxic. 3'et the 

 same species collected in the Cape Province ( and with only a 

 coti])le of weeks' difference in time of collection) did not prove 

 toxic. The specimens of each i)lant were submitted to Dr. 

 Schonland. of (irahamstown. an atithoritv on the South African 

 Crassulacere. but he stated that he was unable to make even a 

 variable dift"erence on an\- t^n'ounds outside of this variation in 

 . toxicity. 



This indicates, therefore, that there is still an interesting" 

 field of research open in this direction for the chemist and phar- 

 macologist, and it is to be ho]:)ed that the gaps in our information 

 on these and similar points may soon be filled u]). 



These remarks conclude om- examination of the broad 

 outlines of the subject with \\liich we are concerned. The pre- 

 sentation of the subject is admittedly im])erfect. and this must 

 necessarily be so. but if the writer has succeeded in arousing a 

 more general interest in the subject than had ])reviously existed^ 

 he will feel satisfied in regarding his object as achieved. 



Hydrocyanic Acid in Sorghum. — The Juunial of 



Agriciiltitnil Nc'scarclr'''- con.tains an account by J. J. \\'illaman 

 and R. M. West on a series of experiments conducted by them 

 in order to ascertain the eft'ect of climatic factors on the propor- 

 tion of hydrocyanic acid in sorg;hum. They foimd that unhealthy 

 plants usuall)- contained more hydrocyanic acid than healthy 

 ones, that an inadequate water-su]:»ply is generally accom])anied 

 by high hydrocyanic acid content, and that there is a pro])ortion- 

 atelv smaller amount of the cyanogenetic glucoside dhurrin in thick 

 heavy stalks than in slender ones. The large amount of hydro- 

 cyanic acid which accompanies inadecjtiacv of water is ascribed 

 to need of glucoside stinuilation when the water supi)ly becomes 

 low, while in the case of unhealthy plants it is thought that a 

 larger c|uantity of glucoside may be produced for the piu'pose of 

 stimulating hormones. 



* (1916) 6 [7], 261-272. 



