i24 



THE CHEMICAL EXAMINATION OF MACROZAMIA SPIRALIS. 



Bv James M. Petrie, D.Sc, F.I.C, Linneax Macleat Fellow op the 

 Society in Biochemistry. 



(From tlte Plii/siological Laboratory of the Universiti/ of Sydney.) 



Historical Importance, and Distribu tion of Cycads 424 



Record of their poisonous Character • . . . 425 



Experimental Work on 3/itrro:tiiiii(i spiralis : Proximate Composition of leaves 



and nuts 429 



Complete Chemical Examination 431 



Feeding Experiment;: 439 



Summary 440 



Historical. — The family of the Cycadaeeae are all tropical or subtropical plants. 

 The genera have a very limited distribution, and are few in number, but these 

 represent the remnants of a once extensive flora which covered the earth in the 

 Palaeozoic and Mesozoic Eras. Scott, in his "Evolution of Plants," says that 

 in the Secondary Floras al)out one plant in every three was a Cyead, and they 

 stretched from the Equator to the Poles. They were the dominant class; there 

 was nothing above them: they were the best thing in the way of flowering plants 

 that their age had produced. Though these in giving rise to the Angiospei'ms 

 gradually became extinct, yet from some less progressive and therefore less highly 

 organised cycadeau forms, we may trace through the Tertiary Era the plants 

 which linger on to our present day. In the descendants of this ancient race of 

 jilants we still find those primitive functions and primitive structures which closely 

 resemble those indicated in the fossils of the Carboniferous Period, and which 

 give to the Cycads a history and an interest uni(|ue among plants. 



The fossil cycadj make their first appearance with the genus PterophyUnm in 

 the Upi^er Carboniferous formations, and reach their maximum towards the end 

 of the Triassic and the beginning of the Jurassic Periods. Of these ancient forms 

 Schimper recognised 34 genera which include 278 species. 



Distribution. — The Cycadaeeae of the present day, according to Engler and 

 tlie Index Kowensis, include mdy nine genera and 75 species. Four genera, in- 

 cluding Zanria, belong to tropical America, two are confined to the African con- 

 tinent, and three are found in Australia. The last include Cyca^ which is widely 

 distributed from India to Japan and through the Islands to Australia, oiu^ Queens- 

 land genus, and 'Macror:amia whicli is limited to Australia. 



