ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 1031 



instance. The secidiospores are mostly oval, varying between 24 by 

 24 /a and 34 by 22 fx ; the epispore is covered with prominent decidu- 

 ous spines, which sometimes become detached in flakes. 



A third species, of which also only the aecidial form is described, 

 is parasitic on Cedrus deodara. The affected " needles " are not dis- 

 coloured, but retain their normal green colour, though they fall early. 

 The spermogonia are very minute, about - 081 mm. in breadth by 

 • 045 in depth, and are for the most part above the level of the 

 epidermis. The secidiospores are spherical or oval, with orange-yellow 

 granular contents, measuring, when dry, about 12 "7 by 8'4/x; the 

 epispore is very thick, and is beset with numerous prominent tubercles. 

 No names are proposed for the last two species. 



Sclerotinieae and Sclerotium-diseases.* — Prof A. de Bary gives 

 an exhaustive account of the structure and development of the two 

 forms of Peziza sclerotiorum Lib. (Sclerotinia Libertiana Fkl., Rut- 

 stromia Karst.), the sclerotium-producing mycelium, and the fructifica- 

 tion. The conditions for the production of the latter form are sufficient 

 moisture and warmth. Sclerotia which had been kept dry for three 

 years were found to be still capable of development ; from one tc as 

 many as twenty apothecia may be produced from a single sclerotium. 

 The hyphse exhibit Errera's glycogen-reaction very beautifully. 



Peziza sclerotiorum must be regarded both as a saprophyte on 

 decaying and as a parasite on living vegetable organisms ; but in the 

 latter case the process of infection is different from what has hitherto 

 been supposed. The spores put out germinating filaments when 

 placed on living organisms ; but these remain short, and do not pene- 

 trate into the tissues ; the fungus becomes capable of infection only 

 when these filaments have obtained a certain development from 

 saprophytic nutriment in a nutrient solution or a dead plant. Free 

 access of air is absolutely essential for its development ; it is nearly 

 indifferent to the action of light. 



With the growth of this fungus is closely connected the formation 

 of a large amount of oxalic acid ; when grown in a nutrient solution 

 containing a lime-salt, the older hyphse become encrusted with calcium 

 oxalate. The oxalic acid is the result of the oxidation of carbohy- 

 drates, and its formation can be shown to take place especially in the 

 immediate vicinity of the fungus-hyphas ; whether in the hyphoe them- 

 selves or not, the author has not at present been able to determine. 

 The irritation caused by the resistance of a solid body to the growth 

 of the hyphse promotes the formation of tufts of organs of attachment, 

 from which is excreted a fluid which penetrates into the adjacent 

 living cells and kills them. These dead cells then produce other 

 fluids which serve as nutrients to the fungus. The parasite, in fact, 

 poisons the living host, and the products of poisoning serve as nutrient 

 materials for its own further development. When it has once entered 

 the living host the mycelium developes with great rapidity ; first of 

 all destroying the protoplasm of the living cells, then the middle 



* Bot. Ztg., xliv. (1880) pp. 377-87, 393-404, 409-26, 433-41, 449-62, 465-74 

 (1 ng.)- 



