Physiologie. — Algae. 7 



Fusan'um in their causal relation to tuber rot and wilt 

 of potato. (Bot. Gazette. LXII. p. 169—209. 13 Fig. 1916.) 



In the introduction the writer brings the history of the genus 

 Fusarium in connection with plant diseases. The writers conclusions 

 ot his own researches are following: 



Fusarium tuberivorutn Wilcox and Link is the same as Fusa- 

 rium irichothecioides Woll. 



Both Fusarium oxysporum and F. trichothecioides can produce 

 both tuber rot and wilt of the potato plant. 



The wilt is induced by destruction of the root System and by 

 clogging of the xylem elements in the stem, and is, in mild cases, 

 raarked by such Symptoms as discoloration of leaves, curling and 

 rolling of leaves. and production of aerial tubers. 



Ünder field and storage conditions Fusarium oxysporum is more 

 probably responsible for wilt than is F. trichothecioides, and the 

 latter more responsible for tuber rotting. 



The Optimum and maximum temperatures of F. oxysporum are 

 higher than those of F. trichothecioides. F. trichothecioides, however, 

 grow's well at 8—10° C, while F. oxysporum does not. These facts 

 may explain in part the fact that F. oxysporum produces more 

 wik than F. trichothecioides, and that the latter causes more 

 tuber rot. 



F. oxysporum has a more rapid, superficial, and spreading 

 habit of growth than has F. trichothecioides. This may be associated 

 with a greater oxygen requirement for i^. ojrys^orwm^ and may account 

 for the frequenting of xylem elements by this fungus. 



Both organisms possess a striking ability to use the most diverse 

 carbon materials as carbon sources in their metabolism. F. oxyspo- 

 rum has a greater ränge in its ability, and can utilize the materials 

 more readily, although not so completely as does F. trichothecioides. 



F. oxysporum is less subject to inhibition in growth and intoxi- 

 cation than is F. trichothecioides. 



Solanin is not toxic to either organism, although it seems to 

 inhibit somewhat the growth of F. trichothecioides. Jongmans. 



Lemmermann , E., Beiträge zur Kenntnis der Plankton- 

 algen. XXVI — XXX. (Arch. Hydrobiol. u. Planktonk. V. p. 

 2^1-338. 36 Textfig. 1910.) 



XXVI. Das Phytoplankton des Paraguay, bei M e d a n o s 

 von Th. Herzog gesammelt. Ein Süsswasserplankton, aus 3 ver- 

 schiedenen Elementen zusammengesetzt: A. Reine Tropenfor- 

 men: l Schizophycee {Microcystis holsatica var. minor), 3 Protococ- 

 coiden {Sorastrum amevicanum , Coelastrum pulchrum var. mammil- 

 latum, Pediastrum duplex var. cohaerens), l Bacillariacee {Surirella 

 Engleri var. sublaevis), 10 Desmidiaceen (z.B. Cosmarium pseudocon- 

 natiim Ndst. f. minor Borge, Staurastrum lepidiim). Die Desmidia- 

 ceen bilden in den Tropen besondere Formen aus, die in den übri- 

 gen Zonen fehlen. — B. WeitverbreiteteFormenderTeiche 

 und Altwässer: 9 Schizophyceen (z.B. Microcystis aeruginosa, 

 Phormidium ambiguum), 3 Flagellaten {Cryptomonas erosa, Euglena 

 viridis etc.', 16 Protococcoideen {Pandorina tnoruin, Pediastrum du- 

 plex etc.), 12 Conjugaten {Cosmarium subcrenatum, Staurastrum 

 brevispinum, Mougeotia minutissima etc.), 35 Bacillariaceen {Melo- 

 sira arenaria, Synedra ulna, Gonyphonema exiguum etc.). — C. AI- 



