624 Fungi. — Bacteria. 



Naematogonium humicola, Penicillium geophilum, humicola und silvati- 

 cuin, Spicaria decumbens und silvatica, Alternaria humicola, Hormoden- 

 ilntni pallidum, Tonil a lucifuga, Ciliciopodium Magnus i, Graph in m , 

 Klebahni, Stysanus difformis, Tilachlidium humicola. 



Interessant ist besonders Minor Saccardoi, weil diese Art die Mitte 

 hält zwischen den Gattungen Mucor und Absidia, das Mycelium mit den 

 Sporangien passen genau bei Mucor, aber die Zygosporen mit ihren Hüll- 

 äclen sind denen von Absidia ähnlich. Went. 



PEIRCE, G. J., The Root-tubercles o f Bur C 1 o v e r (Me- 

 dicago denticulata Willd.) and of some other legu- 

 minous Plant s. (Proc. Cal. Acad. Sei. Botany. III. No. 

 2. p. 295—328. pl. 29. 1902.) 



This is a valuable addition to the extensive literature on 

 root-tubereles. Among the faets and conclusions resulting from 

 a eareful study of the development oi tubercles on the roots 

 of Bur Clover are the following: The bacteria causing root- 

 tubercles are slowly motile, if motile at all, and infect a small 

 proportion of the root hairs by softening or dissolving a small 

 portion of the wall. The infection thread then developed enters 

 the root from the hair growing nearly straight through the 

 cortical parenehyma. The tubercles originate from this infection 

 only endogenously and from the same layer that gives rise to 

 the lateral roots, and are morphologically the same organs as 

 these, though greatly modified as the result of Stimulation due 

 to the presence of the bacteria. The growth of the tubercles 

 is chiefly apical, and the condueting cells do not keep pace in 

 development with the growth of the other elements. The 

 bacteria prevent the formation of starch and cause the degene- 

 ration and almost complete destruetion of the nuclei of the 

 infected cells which are larger than the normal cells and which 

 soon lose the power of division. In the tubercles the infection 

 Strands grow definitely, chemotropically, towards the daughter 

 cells formed by the tubercle meristem, and seem also to move 

 definitely toward the nuclei of the cells into which they penetrate. 

 The presence of bacteria in the cells of the tubercle is injurious 

 to these cells, and the relation to these host cells is that of 

 parasitism, whatever may be their relation to the host as a 

 whole. Hedgcock. 



TRZEBINSKl, J, Influence des irritations sur la crois- 

 sance de la moisissure Phycomyces nitens. (T. ä. p. 

 des Comptes-Rendus de l'academie des sciences de Cracovie. 

 1902. p. 1—40. Avec 1 planche.) 



On a etudie jusqu'ä present l'influence des irritations et 

 leurs effets sur les plantes superieures. Aussi l'auteur du tra- 

 vail se propose de faire des experiences analogues sur les 

 plantes ä thalles et surtout sur Celles dont le thalle n'est pas 

 cloisonne et dont les differentes parties se differencient tot rela- 

 tivement aux fonetions qu'elles remplissent. Parmi les algues ce 

 sont les Siphone'es et parmi les Champignons tout le groupe des 



