126 BOTANICAL NEWS. 



possibly its oospores. Should this be indeed the case their appearance 

 in the Potato-plant in Europe is nevertheless so extraordinarily rare 

 that the question suggests itself whether they do not occur more fre- 

 quently in some other nidus than the Potato-plant, or in any other 

 climate than our own. That they will be regularly found somewhere 

 or other is assumed, for our knowledge of the habits of numerous allied 

 Fungi makes this more than probable. With this interrogation I leave 

 the domain of morphology and return to the phenomena of adaptation. 



As has already been said (page 112), a metoecia or heteroecia in 

 Phytophthora may be considered, not indeed impossible, but highly im- 

 probable ; and if it should exist, there is no indication where to look 

 for it. On the other hand, from the analogy of other Peronosporea, 

 the conjecture readily suggested itself that the Potato-fungus in con- 

 tinuing its development to completion, including the formation of 

 oospores, may make use of some species of host other than the Potato- 

 plant, or, if of it, perhaps in some other climate than ours. I do not 

 exclude from this hypothesis an exceptional occurrence of oospores in 

 our Potatoes in Europe, for we have such a case in Cysto2)us cuhicus, 

 already mentioned. 



What this other presumptive and more favourable host-plant may 

 be, I am as little able to say now as I was fifteen years ago. The 

 Potato-fungus is often found on other species of the order SolanacecB 

 grown in gardens, but without presenting in them phenomena different 

 from those observed when it grows on the Potato-plant ; and, more- 

 over, it is not so frequent on them as on the Potato. In Solanum 

 Pulcamara (a species indigenous to the British Isles as well as to the 

 Continent), it grows only in a starved condition ; it has not yet been 

 observed in other indigenous species. Berkeley has described a case 

 where Phyt. infestans occurred on Anthocercis viscosa, a New Holland 

 plant of the family of Scrophulariace(C, closely related to the Solanacece. 

 On the strength of this, one might ask whether the plant on which 

 the Potato-fungus forms oospores may not perhaps be one of our native 

 Scrophulariacece, say, one of the field weeds of the genus Veronica or 

 Ztnaria. Special investigations in this direction, as well as the 

 examination and comparison of the abundant material made known by 

 the collectors of Fungi, have always yielded a purely negative result. 

 Pkytophthora has not been observed on any indigenous species of 

 Scrophdariacea:, while Peronospora grisea, Ungor. (P. sordida, Berk), 

 plentiful on species of this family, is entirely different from the Potato- 

 lungus. 



( To he concluded in the next number.) 



23otauical |>ctajef. 



Articles in Journals. — February. 



Annals and Mag. Nat. Hist. — M. J. Berkeley and C. E. Broome, 

 " Notices of British Fungi " (nos. 1501-1630. Tab. 9-11). 



Potanische Zeitung. — J. Reinke, "Researches on growth " (tab. 

 2, 3). — L. Cienkowski, " On the Prt/wicZ/rt-condition of Stygcocloniiim " 

 (contd.). — E. Pfitzer, " On the rapidity of the flow of water in the 

 plant." — A. Engler, " On the morphology of Aracece.''^ 



