ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 311 



it was noted that these pits often enlarged and formed an irregular 

 hole ; two such holes might coalesce and nearly sever the fibre. In 

 badly decayed wood, the mycelium itself seems to disintegrate, and the 

 wood cells appear to be filled with a Ijrown substance, probably some 

 decomposition product of the fungus. Tlie chemical changes in the 

 wood were also studied. Similar experiments were made on P. uhnarins. 



Rotting of Potato Tubers.*— (I . Pethy bridge describes a pink rot 

 of potatoes caused by a fungus Fhytophtlwra erythroseptica sp. n. The 

 rot is a rapid one, and an account is given of the development of the 

 fungus, the method of development of the sexual organs being peculiar 

 and novel. " The oogonial incept enters the antheridium at or near 

 its base, grows up through it and out at the top, expanding there to 

 form the oogonium proper in which the oospore develops. It is not 

 certain whether fertilization occurs, but if so it would appear to take 

 place before the formation of the oosphere." 



These observations were made on the fungus in artificial cultures ; 

 the production of oospores and conidia has not been seen on the potato 

 tuljer. Pethybridge contrasts the method of spore-formation in the 

 different species of Phytophthora, and suggests that species similar to 

 P. infestans and to the new fungus should be retained in Phytoplithora, 

 while other species differing in development should be placed in -a new 

 genus Nozemia. 



New Treatment for Silver Leaf Disease in Fruit Trees. f — 

 Sarah M. Baker has applied the theory of enzyme action to the treat- 

 ment of silver leaf. She used a water extract from the deliquescing 

 fruit bodies of Goprinus^ which contain an enzyme powerful enough to 

 destroy their own mycelium. As a result of injecting this enzyme into 

 an attacked branch the silvering of the leaves stopped, and fruit was 

 produced after three years' sterility. Another method of treatment 

 was an external application of the same extract after the manner of a 

 " poultice," at the points of the diseased stem or branch where the 

 SUreum purpureum^ the cause of the disease, makes its appearance. In 

 the latter case the fungal body became greyish in colour and peeled off 

 by degrees. More experiments are being undertaken. 



Protoplasmic Streaming in Mucor.J — The phenomenon of stream- 

 ing has been studied by F. M. Andrews in two species, Mucor stolonifer 

 and M. miicedo. He gathered from his observations that the nutritive 

 medium was of very great importance to the growth of the fungi ; that 

 streaming of the protoplasm is intimately connected with transpiration 

 and is frequently occasioned by osmosis, by the employment of sugar 

 solutions, the rapidity of the streaming corresponding with the concen- 

 tration of the sugar solution. During osmosis there is no peripheral 

 streaming, nor any movement in an opposite direction. Injury to the 

 filament seems to have no influence in starting or in hindering the 



* Sci. Proc. Roy. Dublin Soc, xiii. (1913) pp. 529-65 (3 pis.). 

 + Ann. Bot., xxvii. (1913) p. 172. 



i Bull. Torrey Bot. Club, xxxix. (1912) pp. 445-99 (9 figs.). See also Ann. 

 Mycol., X. (1912) p. 604. 



Y 2 



