Febeuaet 12, 1909] 



SCIENCE 



271 



which are borne solitary spores. Sexual condition 



heterothallie. 



The Interpretation of pre-Persoonian Names, and 



their Bearing on the Selection of a Starting 



Point for Mycologioal 'Nomenclature: Dr. E. J. 



DuBAMD, Cornell University. 



The paper discusses with quotations and ex- 

 amples the difficulties attending the interpreta- 

 tion of the species of pre-Persoonian authors 

 because ( 1 ) the species were based entirely on 

 external characters; (2) specific limits are now 

 much more closely drawn than formerly; (3) 

 microscopic characters, then ignored, are now re- 

 garded as the most important bases for generic 

 and specific distinction, and (4) they as a rule 

 preserved no specimens by which their names can 

 be definitely determined. It is proposed, there- 

 fore, that the date 1753 be abandoned as the 

 beginning of mycological nomenclature and a later 

 one selected, so that these old names may be 

 excluded. The considerations which should have 

 weight in the selection of such a date are then 

 taken up, and a brief history of systematic mycol- 

 ogy given, with the discussion of several possible 

 starting points. The conclusion is finally reached 

 that Persoon's " Synopsis Methodica Fungorum," 

 of 1801, be selected for the following reasons: 



1. The genera and species described before the 

 time of Persoon should be excluded from consid- 

 eration because the majority of them can never be 

 definitely and accurately identified. 



2. Any publication in the modern period is too 

 recent, the bulk of the systematic work having 

 been done before it began. 



3. Its date of publication is early enough to in- 

 clude a great majority of the published names of 

 fungi, and nearly all of those which can be cer- 

 tainly fixed at the present time. 



4. Its publication marks the beginning of the 

 second important epoch in mycological history. 



5. Its author was the originator of systematic 

 mycology. 



6. It can be used as well as any other work as 

 the common point of departure for all groups of 

 fungi. 



7. It is a comprehensive work covering all 

 groups of fungi, and summarizes what had been 

 done before its time, so that it bears about the 

 same relation to the classification of fungi that 

 the " Species Plantarum " of Linnaeus does to that 

 of vascular plants. 



8. Persoon's herbarium is in existence and is 

 available for study, so that most of his names can 

 be fixed with a degree of definiteness impossible 

 for those before his time. 



Adaptations in a Desert Lichen Flora: Professor 



Beucb Fink, Miami University. By title. 

 Successful Inoculations with Peridermimn: 



Geoeqb Gbant Hedqcock, Bureau of Plant 



Industry. 

 Studies of the Potato Fungus, Phytophthora in- 



festans: Professor L. R. Jones and Mr. N. J. 



GiDDiNGS, University of Vermont. 



Phytophthora infestans has been carried con- 

 tinuously in pure culture in the laboratories of 

 the University of Vermont for four years. Start- 

 ing with sterile blocks of raw potato, other cul- 

 ture media have been used with varying success, 

 including raw and cooked potato and pumpkin; 

 potato extract media, including juice from raw 

 potato variously handled, potato broth, and broth 

 with agar or gelatin; pumpkin agar; and several 

 synthetic media solidified with agar. 



Longevity. — Sealed gelatin cultures seven months 

 old remained alive, but were slow in starting. 



Noteworthy Morphological Characters Oiserved. 

 — Haustoria-like branches in potato tissue as de- 

 scribed by Delacroix. Abundant septation in old 

 cultures. Apparent differentiation in some cases 

 into two strains, the one exceeding the other in 

 vegetative vigor. Oogonla-like bodies sparingly 

 produced on certain media, frequent on others. 



Concerning Infection and Disease Resistance. — 

 Sporulation may occur in diseased tubers before 

 digging and in storage. Infection occurs usually 

 through eyes, but occasionally through wounds or 

 lenticels. Wide differences occur between varie- 

 ties (e. g., Early Rose, vs. Irene) as to ease of 

 leaf infection and subsequent rate of spread; lead- 

 ing to conclusion that disease resistance of leaves 

 may reside in mesophyll as well as possibly in 

 epidermal tissues. 



Similar differences occur in the rate of develop- 

 ment upon sterile blocks cut from the interior of 

 potato tubers, e. g., Ionia seedling vs. Irene. This 

 difference is not due to the acid reaction of cell 



Artificial Cultures of Phytophthora vnth Special 

 Reference to Oospores: Dr. G. P. Clinton, Con- 

 necticut Agricultural Experiment Station. 

 In the 1905 Connecticut Agricultural Experi- 

 ment Station Report the writer gave results of 

 experiments with artificial cultures of Phytoph- 

 thora infestans. The oospores, which are as yet 

 unknown, did not develop in these. However, the 

 oospores of Phytophthora phaseoli, described for 

 the first time, readily developed in the cultures. 

 The past fall specimens of the recently described 



