ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 273 



ferax, and the tadpole, which had hitherto heen lively, soon hecame 

 more sluggish in its movements ; its body quickly became covered with 

 filaments of Saprolegnia, and within two days after infection it died. 

 The protoplasm of the filaments of the parasite on the body of the fly 

 was found to be transformed into thousands of zoospores, which, by 

 means of their two cilia rapidly diffused themselves through the water. 

 This observation shows that a single dead fly may become the focus of 

 infection of a large number of aquatic animals. The whole surface of 

 the tadpole was covered with Saprolegnia, so that death must have been 

 produced by the suppression of the action of the skin. The tadpole in 

 the other vessel was not affected. 



Elaphomyces.* — Drs. M. Eeess and C. Fisch discuss the physiological 

 relationship of this fungus to the roots of fir-trees, on which it is usually 

 found, and contribute some additional knowledge to its life-history. 



The authors regard the fungus as a true parasite on the roots of fir- 

 trees. It is never found at any great distance from them, and all 

 attempts failed to induce the spores to germinate either in the soil or in 

 nutrient solutions. It attacks only the primary root, which it completely 

 envelopes without apparently injuring it ; the secondary roots pierce 

 through this envelope and are not attacked by it ; but the authors were 

 unable to determine the mode in which the root obtains its nutriment 

 from the soil, or whether there is any true symbiosis between it and the 

 fungus. 



The development of the receptacle is described especially in Elapho- 

 myces granulatus and variegatus, which agree in essential points. The 

 rudiment of the receptacle consists of a ball of mycelium with a number 

 of intercellular spaces filled with air. A central hyaline nucleus is then 

 differentiated from the surrounding slightly yellowish outer layer, which 

 developes into pseudo-parenchyma, and is known as the " cortex vitta- 

 dinis," while the central mass becomes the true peridium with its 

 ascogenous tissue. The ascogenous hyphae do not spring from the 

 primary hyphre of this tissue, but from special shoots proceeding from 

 the hyphal tissue which clothes tho interior of the periderm, and push 

 themselves between the loose tissue of .the gleba. The mature fructifi- 

 cation consists of three distinct portions, cortex, peridium, and gleba. 

 The asci originate as club-shaped or conical swellings on terminal or 

 lateral branches of the ascogenous hyphaa, and are distinguished from 

 all asci hitherto known by the fact that the septum which separates 

 them from their supporting filament does not make its appearance till a 

 comparatively late period, even after the young spores have begun to be 

 formed. The number of spores in an ascus varies between 1 and 8. The 

 cells of the cortex develope at particular points into the projecting warts 

 which characterize the mature fructification. 



Cabbage-Hernia.f — Dr. J. Brunchorst discusses the problem of the 

 best way of obviating the loss caused by the fungoid ravages of Plasmo- 

 diophora Brassicds among cabbages. It seems useful to change the stock, 

 but the young plants are often infected in their seed-beds, and the 

 disease is as bad as ever. He has therefore been led to experiment with 

 bisulphide of carbon as a disinfecting agent for the soil ; and his results, 

 of which the statistics are given, have been most successful. 



* Uhlworm and Haenlein's Bibl. Bot., Heft vii., 24 pp. and 1 pi., 1887. 

 t Btrgens Mus. Aarsberetning for 1886 (1887) pp. 227-31. 



