Physiologie. 35 



the transformation in the behaviour ol' living tissues within a com- 

 paratively short time. 



In the preparation of a Standard extract, the Botrytis was grown 

 on Potato mush agar, the mycelium scraped off, filtered and the 

 spores centrifuged out in practicaily a pure form. These were dis- 

 tributed uniformly in turnip extract (1 cc spores to 10 ccs liquid) 

 over a levelled glass plate in a large petrie-dish and allowed 23 

 hours to germinate at room temperature. They are then washed, 

 dried, ground to a powder and extracted for 1 hour in the Propor- 

 tion of 2 gr to 3 cc of water, this being cleared by centrifuging. 



The extract was tested on discs of tuber I — 1-| cm by ^ mm 

 thickness, the basis of the method being its capacity to destroy the 

 coherence of the tissue. This method is limited by 1. The Nature of 

 the tissue employed. 2. The accuracy in thickness of the sections. 

 3, The determination of the end-point of the reaction. 4. The varying 

 nature of the actual Substrate. 5. The stability of the extract. 



The action is of a twofold nature 1. Action on the cell wall 

 leading to disintegration of the tissue. 2. Action on the protoplast 

 producing death. 



On the soft tissues of higher plants the action is rapid; on hard 

 Woody tissues absent. Mosses and Hepatics are resistant. The post- 

 mortem changes brought about by the fungal extract are identical 

 with those induced by the fungus, and it is considered ihat all the 

 macerating and lethal effects of the fungus can be explained on 

 the basis of the properties of the Standard fungal extract. 



Microscopical investigation shews that death of the cells takes 

 place at a late phase of the process of disorganisation of the cell wall. 



Physical and chemical relationships of the extract are considered 

 and it is shewn that the activity of the extract as regards both 

 macerating and lethal effects is totally destroyed by heating, by 

 mechanical agitation and by neutralization with Alkali. 



The relations of the extract to diffusion and dialysis are briefly 

 stated. 



It is found that neither oxalic acid nor Oxalates play any part 

 in the toxicity of the extract and if any special lethal substance is 

 present it must be of colloid nature. 



The only active substance in the extract appears to be the 

 enzyme which produces, a macerating action mainly by Solution of 

 the middle lamella. The enzyme appears also to be responsible for 

 the lethal action of the extract, the death of the cells, being brought 

 about either by direct action of the enzyme on the protoplastic 

 membrane or indirectly as a result of the action upon the cell walls. 

 The ability of certain tissues to resist the action of the extract is, 

 dependent upon the special properties of their cell walls. 



W. B. Brierley (Kew). 



Wilfarth, H., H. Roemer und G. Wimmer. Einfluss der 

 Phosphorsäure auf Wachstum und Beschaffenheit der 

 Zuckerrüben. (Zeitschr. Ver. deutsch. Zucker-Industr. LXII. p. 

 1037—1107. 1912.) 



Es ergaben die umfangreichen Untersuchungen folgendes: 



1. Bei gleicher Phosphorsäuredüngung wird durch steigende 



Stickstoffgaben die Qualität der Rüben herabgesetzt und dieses um 



so mehr je kleiner die Phosphorsäuregabe war; bei gleicher N-Dün- 



gung wird mit steigender Phosphorsäuregabe die Beschaffenheit der 



