till! SUMMAKY OK CURRENT RESEARCHES RELATING TO 



primordia of the principal parts of the fruit-body, pileus, hymenophore 

 and stem are endogenous in origin and are differentiated within the 

 central portion. The enveloping zone of loose-meshed tissue is the 

 "universal veil" or blematogen, homologous with a similar layer in 

 Amanitopsis vaginata. The "partial veil "of these Agarici is a structure 

 sui generis, being formed by the downward and inward growth of the 

 margin of the pileus primordium, and forms the annulus or ring. 



In Agaricus campestris there is an additional "universal veil" 

 consisting of a delicate floccose layer which becomes torn into patches. 



Studies in the Physiology of Parasitism.* — W. E. Brown has 

 been able to advance our knowledge of parasitism by his experiments 

 with the mycelium of Botrytis cinerea. He obtained a powerful extract 

 by germinating the spores and extracting the juice from the germinat- 

 ing tubes. This solution he applied to living tissues and reports the 

 results. 



The action of the fungus extract he found was twofold : (a) Action 

 on the cell-wall, leading to disintegration of tissue (macerating) ; and 

 (b) action on the protoplast, producing death (lethal). He found that 

 lethal action took place at a late phase of maceration. Accounts of the 

 different experiments are given. 



The extract may be rendered innocuous by heating, by mechanical 

 agitation, and by neutralization with alkali. " Deactivation," the term 

 used by Brown, leads to the loss of the lethal power of the extract. 



The active substance of the extract appears to be the enzyme, which 

 dissolves the middle lamella and causes the death of the cell by direct 

 action on the protoplasmic membrane, or indirectly as a result of the 

 action on the cell-walls. Certain tissues are able to resist the action of 

 the fungus owing to special properties of their cell-walls. Neither oxalic 

 acid nor oxalates play any part in the toxicity of the extract. If any 

 special lethal substance is present it must be of colloidal nature. 



Fungi as Cellulose Destroyers.f — F. M. Scales has investigated 

 the action of filamentous fungi on cellulose in soil such as humus, etc. 

 He found that fungi were even more effective than bacteria in their 

 action on cellulose. In the course of experimentation uineteen species 

 of cellulose-destroying filamentous fungi were identified, and two new 

 ones found. One of these latter was found to produce a very active 

 cytase. Cultures were also made with ammonium sulphate and with 

 peptone as the source of nitrogen supply. With the latter many of the 

 organisms failed to attack the cellulose. It is suggested that this is due 

 to the carbon in the peptone which was utilized by the fungus, and 

 satisfied its requirements. 



Diseases of Onions. $ — Jun Hanzawa has discovered a new fungus 

 disease of Allium Cepa due to Fusarium C'epse s^.n. The plants that 

 are attacked and can be detected by the decolouration of the leaves 

 which fall tow r ards the ground. The whole plant loosens from the soil 



* 



Ann. Bot., xsix. (1915) pp. 313-48. 

 t Bot. Gaz., lx. (1915) pp. 149-53. 

 t MycoL Centralbl., v. (1914) pp. 4-13 (2 pis.). 



