366 SUMMARY OF CURRENT RESEARCHES RELATING TO 



singula v. raro bina, lateraliter inserta, sessilia, trichogyno simplici 

 praedita ; cellulse ascogenae tres v. plures ? ; asci maturi[non visi ; sporae 

 septatae. 



Mr. K. Thaxter * publishes preliminary diagnoses oi no less than 

 96 new species of Laboulbenia, found on zoological specimens in various 

 public museums. 



Multiplication of Yeast without Fermentation and with Limited 

 Quantity of Air.f — M. A. Eosenstiehl records instances of the multi- 

 plication of yeasts in saccharated media and in presence of a limited 

 quantity of air. 



The occurrence of this lowered vitality was observed in yeasts 

 obtained from fermenting cider and isolated on plates composed of 

 apple-juice thickened with gelatin or agar. When transferred to a 

 medium composed of acidulated malt infusion, invert sugar, and tartaric 

 acid, they were found capable of fermenting apple-juice after two or 

 three cultures in the artificial must ; but if transferred directly from 

 the plates to the juice, they were powerless to excite fermentation ; they 

 sank to the bottom of the fluid and began to increase in bulk. Examined 

 microscopically the sediment showed that the yeasts were budding 

 actively. Experiments are then recorded indicating that the tannin of 

 the apple or some analogous substance coagulable by gelatin is the 

 cause of the phenomenon. Hence, of the two forms of vital activity 

 exhibited by yeast, fermentation is extinguished before reproduction 

 when the vitality of the organism is lowered or enfeebled. 



Parasites of Wheat.} — M. L. Mangin has studied in particular the 

 disease of wheat produced by Septoria graminum and that^ known as 

 pietin. 



The spores of Septoria graminum put out germinating filaments 

 which perforate the epiderm, but do not enter through the storaates ; 

 their action is purely chemical. The specific characters of this fungus 

 at present given are not constant. Its ascospore form is as yet un- 

 known. 



Pietin is a disease which attacks the haulm of the wheat, and is 

 caused by Leptosphseria herpotrichoides, often accompanied by Ophiobolus 

 graminis ; also by Pyrenophora trichostoma, and by the conidial forms 

 of Dictyosporium opacum (?), Coniosporium rhizophilum (?), and Asper- 

 gillus circinatus sp. n. The peritheces of Opliiobolus emit their asci, 

 which discharge bacilliform spores. These, on germinating, give out 

 a short promycele or none at all, and develope minute motile sporids. 

 The asci of Leptosphseria burst within the perithece, and discharge the 

 ascnspores, enclosed in a gelatinous matrix which swells up and becomes 

 disintegrated in water. Culture experiments demonstrate that Dictyo- 

 sporium opacum (?) is the conidial form of Leptosphseria herpotrichoides, 

 and that Coniosporium rhizophilum (?) is the conidial form of Ophiobolus 

 graminis. 



Teleutospores of Puccinia.§ — Mr. H. H. Hume describes and figures 

 examples of several species of Puccinia — P. heterospora, tomipara r 



* Proc. Amer. Acad. Arts and Sci., 'xxxv. (1899) pp. 153-209. Cf. this Journal, 

 1897. p. 319. t Comptes Reudus, cxxx. (1900) pp. 195-8. 



1 Overs, k. Danske Vidensk. Selsk. Forhandl., 1899, pp. 213-72 (3 pis. and 

 17 figs.) (French). § Bot. Gazette, xxviii. (1899) p. 418-23 (6 figs.). 



