Algae. — Eumycetes. 41 



Topfpflanze von Hederä) erläutern Verf. auch diese zweite Methode, 

 welche gegenüber der ersten mehrere Vorteile besitzt. Zum Schluss 

 geben Verfif. noch einige Anhaltspunkte zur Vermeidung von Feh- 

 lerquellen. Losch (Hohenheim). 



Stewart, G. R., Availability of the nitrogen in Pacific 

 coast kelps. (Journ. Agric. Research. IV. p. 21 — 38. 1915.) 



In preparing dried and ground kelp as a fertilizer the availa- 

 bility or readiness with which the nitrogen in it is changed to 

 ammonia and nitrates in fresh field soil was found to vary with 

 different species and with the manner of preparation. 



The nitrogen of Nereocystis luetkeana is relatively very available, 

 while that of Pelagophycus porra is less readily changed. These two 

 varieties are of minor commercial importance. 



Macrocystis pyrifera, the commercial variety, is very slowly 

 changed in the soil. 



The availability of the nitrogen of M. pyrifera is greatest when 

 the kelp is added in a fresh or only partially dried condition. 



The availability of its nitrogen decreases materially when 

 Macrocystis is fully dried. 



Removing a large portion of the salts from either fresh or dry 

 Macrocystis by leaching does not cause it to decompose more readily. 



Macrocystis must be dried tili crisp in order to grind readily. 

 This drying should not be continued longer than necessary, and 

 the kelp should not be scorched or overheated. 



The addition of moderate quantities of Nereocystis to a sample 

 of fresh soil in the laboratory did not cause any great interference 

 with either ammonification or nitrification of readily available organic 

 matter, such as dried blood. 



Similar experiments with Macrocystis showed at first a decrease 

 in the rate of transformation, especially in nitrification. This decrease 

 did not continue and as time passed the ammonification and nitri- 

 fication became practically normal. 



When using kelp in field practice, it is probable there would 

 be no interference with either ammonification or nitrification from 

 either the kelp or the salts present in it. Jongmans. 



Hepwerden, M. A. van, Over den aard en de beteekenis 

 der volutine in gistcellen. [Ueber die Natur und die 

 Bedeutung des Volutins in Hefezellen], (Versl. gew. 

 Verg. Kon. Akad. Wet. Amsterdam. Afd. "Wis.- en Nat. XXV. 

 p. 1445—1463. 1917.) 



Als Zusammenfassung der von der Verf. erhaltenen Ergebnisse 

 bezüglich des vielumstrittenen Volutin-problems darf folgendes 

 gelten : 



Die Bildung der Volutinkörner in Pilzen und Hefezellen ist von 

 der Anwesenheit anorganischer oder organischer Phosphorver- 

 bindungen im Nährboden abhängig. Auf phosphatfreiem Nährboden 

 kann Ustilago maydis, Torula nionosa, Saccharomyces cerevisiae 

 und Lactosehefe gezüchtet werden, ohne Volutinbildung in den 

 Zellen. Beim Ueberimpfen auf phosphathaltigen Boden wird Volutin 

 sofort neugebildet. 



Verdünntes Alkali entzieht den Kulturen der Torida monosa 

 oder der Saccharomyces cerevisiae mit dem Volutin auch eine 



