NOTES ON EECENT EE SEARCH. 



269 



in certain families has long been known, and it was assumed by a too 

 facile oecology that its importance lay in the protection which it was 

 assumed to afford, by reason of its poisonous properties, against the 

 depredations of animals. It is only recently that the matter has been 

 seriously investigated." — B. I. L. 



The Genus Pythium. 



Pythium ultimum, n. sp., Observations on the Biology and 

 Cytology Of. By A. H. Frow, D.Sc, F.L.S. (Ann. Bot. vol. xv., 

 No. lviii., p. 269). — Pythium is a genus of considerable interest to 

 gardeners. When seedlings are found to damp off, or even soft cuttings, 

 it is very likely that the trouble is due to a Pythium, encouraged by too 

 much moisture. The whole story is most interestingly told and clearly 

 explained by Professor Marshall Ward in his "Diseases of Plants," and 

 he alone in this country appears to have paid attention to the genus. In 

 the present paper we have a further important study devoted to the life- 

 history, cell structure, and development of *a new species, which is fully 

 described and illustrated. Unlike Pythium de Baryanum, the common 

 species, it appears to be purely saprophytic, and w r as found in rotten Cress 

 seedlings grown for the purpose of obtaining Pythium material. Since 

 this new 7 species cannot attack a living plant it is not in itself a foe to be 

 understood and guarded against ; but the paper dealing with it, accom- 

 panied by many illustrations, is valuable for a study of the genus. It is 

 allied to Peronospora, and relatives account for many of the diseases to 

 which plants are liable. — B. I. L. 



Haustoria. 



Rhinanthacese-Haustoria (Beih. Bot. Cent. bd. xi. ht. 7, pp. 437- 

 485 ; plate). — Herr Adolf Sperlich gives a detailed account of the anatomy 

 and contents of the absorbing suckers on the roots of Melampyrum, 

 Tozzia, Alectorolophus , and Pedicularis. Melampyrum pratense, sylvati- 

 cum, and nemorosum are shown to be both saprophytic and parasitic, 

 the haustoria of the same plant being attached to both dead organic 

 matter and living roots. The hyaline tissue of the haustoria is formed 

 from divisions of the pericambium and endodermis. Tracheids are not 

 always present, and are frequently wanting when the haustoria are attached 

 to dead material. The haustoria (Melampyrum) possess differentiated 

 rows of tracheids, w T hich are in connection with strands of irregularly 

 thickened cells which penetrate the host-root. The end cells of these 

 strands are often elongated, like the hyphae of a fungus mycelium, and 

 grow through the host. The contents of the haustoria consist of 

 albuminoid crystals in the nuclei of the cortex and hyaline tissue, of 

 bodies resembling (as regards constitution) the " bacteroids " of legu- 

 minous root-tubercles, of starch, of amylodextrin, of (probably) glycogen, 

 of Rhinanthin, of phosphoric acid, and of nitrates. The hyaline tissue 

 is rich in albuminous matters. Similar results were obtained for Tozzia, 

 Alectorolophus, and Pedicularis. The author concludes that both nitrates, 

 phosphates, and also organic food material are obtained by the haustoria. 



