Pkthybridgk & Laffeuty — Disease of Tomato and other Plants. 497 



that the old genus Phytophthora should be divided. It was proposed that 

 only those species with amphigynal antheridia should remain in this genus, 

 and that the other species, with paragynal antheridia, formerly included in it, 

 should be made to constitute a new genus, Nozemia. This suggestion has 

 been followed by Murphy (3), who has recently published a detailed account 

 of the morphology and cytology of the sexual organs of P. erythroseptica, but, 

 unfortunately, not by Eosenbaum (11) in his statistical studies of species of 

 the two genera. The latter author has, however, shown that the surmise as 

 to the true character of the sexual organs in P. omnivora var. Arecae, above 

 referred to, was correct (10). 



Since that time five other species of Phytophthora have been described by 

 the following authors: — Butler and Kulkarni (1); Dastur (2); Tanaka 

 (Swada) (12) ; and Sherbakoff (13), in which the sexual organs are of the type 

 found in P. infestans, the earliest described member of the group. The follow- 

 ing is a list of all such species described up to the present : — 



(1) P. erytliroseptica Pethyb. (6) P. C'olocasiae Eacib. 



(2) P. infestans de Bary. (7) P. Allii Saw. 



(3) P. Phaseoli Thaxt. (8) P. Melongenae Saw. 



(4) P. Arecae (Golem.). (9) P. terrestria Sherb. 



(5) P. parasitica Dast. 



It seems possible, judging from the published descriptions alone, that the 

 last two species in this list may be identical, but this can only be decided by 

 a careful comparison of pure cultures of the two. 



The question arises as to whether the fungus which causes the disease of 

 tomato plants described in the present paper is identical with any one of those 

 enumerated above, or whether it must be regarded as a new species hitherto 

 undescribed. Prom a careful study of the published descriptions we conclude 

 that our fungus cannot be identical with any one of the above nine, but it is 

 scarcely necessary to discuss the points of difference in detail here. The 

 sporangia of the above-mentioned nine species, with the exception of P. 

 erythroseptica, are all more or less distinctly papillate, while those of our 

 fungus resemble those of the last-named species in being blunt or rounded at 

 the apex. 



Our fungus most nearly resembles P. erythroseptica, but differs from the 

 latter in the size and colour of its sexual organs and also in its remarkable 

 reluctance to produce sporangia and oospores in quantity. A long series of 

 parallel cultures and infection experiments was carried out with these two 

 fungi, into the details of which it is not necessary to enter here. It is 



4 h 2 



