8 The Shee^^'Fluke. 



favourite studies, and who are now for the most part beyond the reach of I 



any honors, except those which we pay to the illustrious dead. 



While profiting from their discoveries let us not forget who are our bene- 

 factors.* 



The Sheep-fluke in Australia. 



A country swarming with sheep, like Australia, was sure, sooner or later, 

 to suffer from the ravages of the sheep-fluke. From times early in the 

 history of the country down to the present, losses of sheep from this pest 

 have been frequent, especially in certain districts. 



It is not the intention here to more than hint at the history of the 

 sheep-fluke in Australia. The reader will perhaps be content with the bare 

 statement that could the losses from this pest all be recovered they would 

 far more than pay the national debt of all Australasia. 



It is much more the author's present purpose to ask whether the peculiar 

 conditions of Australia have given rise to any new problems in connection 

 with this pest, and, if so, whether these problems are soluble, and to state a 

 few of the results of his own observations. 



Whether Australian conditions have given rise to new problems in con- 

 nection with the life history of the sheep-fluke is a question that rose pro- 

 minently in my mind after my inquiry into the life-history of the Austra- 

 lian wheat-rust. t The parallel between the life-histories of rust and fluke, 

 notwithstanding the fact that one is an animal parasitic in other animals, and 

 the other a plant parasitic in other plants, is so curious, and, 1 venture to 

 think, so instructive, as to deserve consideration. 



The fungus commonly known as wheat rust is found in Europe to pass 

 one of the stages of its existence in the tissues of the leaves of the barberry 

 bush. In this latter situation its full growth is attended with the produc- 

 tion of two sorts of spores, and these two sorts of spores have given rise in 

 some quarters to the opinion that the fungus in this form is a complete 

 organism in which a sexual reproduction is possible — witness the words 

 spermogonia and spermatia applied to the so-called male organs and 

 sporidia respectively ; at any rate, whether this view be entertained or not, no 

 one, I venture to say, will deny that the rust-fungus reaches one of its highest 

 stages of development in the form in which it appears in the tissues of the 

 barberry-bush, and this is entirely sufficient for the purposes of our parallel. 

 The spores of the barberry-leaf-form of rust alighting on the blades of wheat 

 produce a second generation unlike the first, and the spores of this second 

 generation again, later in the season, give rise to a third generation unlike the 

 second, and finally the third generation produces the following spring a 

 fourth, which, when used to infect the barberry-bushes produces the original 

 barberry-rust. 



Now, this cycle of generations is as remarkable as that of the sheep-fluke, 

 and curiously like it in a variety of ways. I do not wish to make too much 

 of this analogy, for it is well-known that analogy is often very misleading ; 

 but I may justly call attention to the following fact, and with it point a 

 moral. My investigations have conclusively shown that, although the above 

 is a correct sketch of the life history of the wheat-rust in Europe, it is not 

 correct for Australia. There are few barberry -bushes in Australia, and on 

 the few that exist no barberry-rust has ever been seen, from which we can 

 only draw the conclusion that the barberry-rust either does not occur in 



* Wageuer, Bojanus, von Baer, Steenstrup, de Filippi, Moulini^, de la Valette, 

 Leuckart, Thomas, and many others. t Puccinia graminis. 



