Addenda. 2 1 9 



Model Farm, Glasnevin, couufcy Dublin. Mr. Pirn 

 kindly forwarded examples to us, and he soon after- 

 wards published an illustrated account of tlie discovery 

 in the Gardener's Chronicle for 22nd December, 1883. 

 Mr. Pirn's examples were remarkable for being 

 infested witli a parasitic fungus, and one apparently 

 till now undescribed. The parasite grows on the 

 Tsaria, breaks up its tissues, and more or less absorbs 

 its crimson colour. The parasite is a Sairrolegnia 

 allied to S.ferox, Kutz., of the salmon disease, but 

 diiferentin many important characters.'"' 



The new parasite, which may be termed Saprolegnia 

 jiMlomulies, W. Sm., is illustrated at fig. 24, enlarged 

 400 diameters. The circular bodies ai-e sporangia, 

 zoosporangia, or spore-cases of unusually large size 

 and filled with small motile spores or zoospores. In 

 the largest siDorangium illustrated the zoospores are 

 germinating within the sporangium, and protruding 

 their germ-tubes through its gelatinous wall. A 

 remarkable character in this parasite is found in the 

 septate or jointed mycelium, an unusual character in 

 the Saprolegniie, in the mycelium carrying numerous 

 conidia, and in the sporangia and mj^celial threads 

 often becoming confluent. 



In the Dublin examples the sporangia were so 

 abundant that all parts of the Isaria threads were 

 covered, they were so crowded together that they took 

 penlagonal and hexagonal instead of circular forms. 

 ]\Iany sporangia were sessile, or intercalated in the 

 mycelium, whilst others were shortly stalked. Antlie- 

 ridia were rare. The jointed mycelium formed a dense 

 transparent stratum over the host plant. In some 



