229 



possible. The history of eacli species is very fully given, 

 especially those which are of horticultural importance, and there 

 is an exhaustive list of references and figures. In a number of 

 cases materials were not available for illustration. The numerous 

 hybrids are also very fully indicated, and in those cases where 

 they have formed the starting point of distinct races of garden 

 Roses, the history, and an illustration are also given. The last 

 number contains a number of Chinese Roses received too late for 

 inclusion in their proper sequence ; several of these are new, and 

 others are figured here for the first time- They are partly from 

 Roses communicated by M. Leveille, and partly from seedlings 

 raised at Warley from seeds collected by Mr. E. H. Wilson, whose 

 travels in China have resulted in several interesting additions to 

 the genus Rosa. Of tbe beavity and accuracy of the plates it is 

 difficult to speak too highly, and Miss Willmott must be con- 

 gratulated on the production of a work that will form a landmark 

 in the history of this beautiful and difficult genus. r. a. r. 



Poisoning by Sorghum haiepense. — Some recent corre- 

 spondence in the '* Indian Forester/^ vol. sxxis, nos. 6 and 10, 

 upon the value of Sorgliufn haiepense^ Pers., as a fodder grass, and 

 the danger to cattle and horses which its use entails, shows that the 

 exact nature and reactions of the dangerous constituent are not 

 well understood- There is conclusive evidence that the young 

 vegetative parts of S, haiepense are, under certain conditions, 

 poisonous to farm animals, and as the plant is, after rice, probably 

 the commonest food and fodder plant in India, besides being much 

 used elsewhere, it has been deemed desirable to publish a short 

 note dealing with the matter. 



In 1902 Dunstan and Heniy (Phil. Trans. Roy. Soc. A, 199, 

 p. 399), isolated a glucoside, w^hich they called dhurrin, from the 

 leaves of the great millet [Soi^ghnm vulgare). This substance was 

 found to have the empirical formula Ci4 Hit Ot N, and on hydro- 

 lysis with hot dilute hydrochloric acid or the enzyme emulsin, 

 yielded one molecule each of prussic acid, parahydroxybenzalde- 



hyde, and dextrose. 



Sorghum haiepense^ Pers. (Andropogon halepensts, Brot.), is 

 considered by Hackel to be a variety of S. vulgare, Pers. (AndrO' 

 pogon Sorghum, Brot.), and there is little doubt that dhurrin is 

 found in it as well as in the typical plant. The free prussic acid 

 is the actual substance which causes the death of animals eating 

 the young vegetative parts of SorghuTti. The enzyme emulsin is 

 present in the parts of the plant containing the glucoside, and 

 when in the early processes of digestion the two come together the 

 emulsin by the addition of water to the dhurrin breaks the latter 

 down and liberates the poisonous prussic acid. 



An examination of the numerous records of cases in which 

 SorghuTTh was used for fodder establishes two facts of practical 

 importance. Firstly, the young vegetative parts of the plant are 

 the most dangerous to stock, the mature plant being nearly or 

 quite harmless. Analyses of old plants have shown that little or 

 no prussic acid yielding substance was present. Secondly, the 



