Fungi, Bacteria und Pathologie. 419 



From further experiments the author comes to the conclusion that, 

 the conidia of the iirst generation produced on leaves of a stränge liost- 

 plant previüusly subjected to the acti^n of heat, aicohoi, or other, do 

 not acquire the power of infecting normal leaves of their temporary host. 

 This appears to give some evidence in favour of the idea of the heredi- 

 tary nature of the infection powers of some biologic forms. 



Ä. D. Cotton (Kew). 



Ward, H Marshal, Recent Researches on the Parasi- 

 tism of Fungi. (Ann. Bot. XIX. Jan. 1905. p. 1—54.) 

 [An adress delivered before Section K. British Association, 

 at Cambridge. 1904.] 



An historical survey is first given of the progress of mycoiogy 

 during the past Century, after which the author limits himself to the dis- 

 ciission of recent researches on the Uredlneae. 



The saiient features of modern werk on this branch are considered 

 under the following headings : germination of uredospores, specialized 

 parasitism, immunity, susceptibility, mycoplasm, and infection. 



The writer maintains his position as to the mycoplasm theory, and 

 states that pure cultures give no evidence that lends support to that 

 hypothesis. Ke believes that the entering germ tube and substomatal 

 vesicle would be discovered, if serial sections were cut through the 

 patches at the margins of which „protomycelium" and „mycoplasm" are 

 found. He maintains, that the mycoplasm hypothesis has arisen through 

 reading the phenomena backwards. 



Some new points of interest are brought forward in connection with 

 the authors most recent work on Piiccinia glumariim. He finds that in 

 „immune" forms of wheat, the uredospores germinate and send out tubes 

 into the stomata in the usual way, but the hyphae sonn exhibit a star- 

 ved appearance, and undergo death changes about the sixth day. The 

 conclusion arrived at is, that the fungus attacks the host cells with such 

 vigour that it kills them almost immediately and itself thus becomes a 

 victim to starvation. 



As to „bridging species" the author states, that he is convinced that 

 it is here we have a clue to the phenomenon of the ever widening cycle 

 of adaptation. In 999 times out of 1000 the spores adapted to a small 

 given circle of host plants cannot successfully break through the de- 

 fences of another circle. But in the thousandth case a spore may infect 

 an allen host and once established its progeny can go on infecting the 

 new host. The evidence compels us to believe, that the host reacts 

 upon, and affects the physiological powers of the fungus; the effects are 

 invislble and produce no distinguishable morphological Impression on 

 the spores. But if very slight morphological results should follow, we 

 have then the clue to the graduation of morphological differences, suffi- 

 ciently distinct for the determination of species. 



Various cases are mentioned in which a fungus is in the process 

 Ol Splitting up into incipient biological species. It is remarked that such 

 adaptations may be local; for instance, it is possible that a Piiccinia 

 which in a given geographical area is in the habit of infecting one alter- 

 nate host, may^ in a different area where that host is absent, have to 

 adapt itself to another. 



The füll paper on Puccinia glumarum will appear later. 



A. D. Cotton (Kew) 



Weil, E., lieber den Mechanismus der Bakterien- 

 agglutination durch Gelatine. (Ctrbl. für Bakt. 

 Abth. I. Bd. XXXVII. 1904. p. 426.) 



Gelatinelösung zeigt ganz ähnliche Agglutination wie typische 

 „Agglutinine". Zwar kann durch wiederholte Benützung zu dem Ver- 

 such, Gelatine die genannte Eigenschaft verlieren, trotzdem beweisen die 



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