._ 309 — 



In a separate glass are placed the turions wintered in culture after 

 having been cleaned of the adhering part of the mother-plant. These 

 plants have almost the same appearance and size as the above experi- 

 ment-plants, wintered in nature. 



April 22. — The Mijrio])hyllum-p]3in[s are now c. 40 — 50 cm. in 

 length and have begun to develop side-branches; the most part of these 

 are still on a quite young stage. 



May 1. — The first outcome of an infection observed. One of the 

 plants in the infected culture appears curled in the top, and in the axil 

 of a single leaf is developed a swelling of hardly 1 mm. across. On 

 microscopic examination the slender mycelium with many vesicles rather 

 rich in oil is seen in the interior of the swelling ; the periferic parts of this 

 is free from the mycelium and rich in starch. 



May 15. — On the whole 12 plants are infested by the fungus in 

 the infected culture. Especially the side-branches are often infested (cp. 

 also Rostrup 1. c). By a single infection is produced either a single 

 swelling, or more are developed near each other by wandering of the 

 mycelium. This can thus be more or less extended, but the probability 

 of wintering (in the rhizomes or turions) is a priori little, the mycelium 

 being very slender and perishable; in good accordance to this is the fact, 

 that our turions, wintered in culture, though coming from very violently 

 infested mother-plants, on growing forth appear entirely sound. — The 

 control-plants are all fully normal. 



Early in June. — In the past ca. 3 weeks no more plants have been 

 infested in the infected culture; the attack of the fungus has thus ended. 

 The plants wintered in culture are constantly sound. The control-plants 

 fully normal. 



Myriophyllum alterniflorum D. G. 



In the fall 1908 we collected in the lake Gurre So in northern 

 Seal and some specimens oi Mijriophyllum alterniflorum for the purpose 

 of trying the infesting power of Cladochytrium against this plant — and 

 further to study the wintering of this species, not sufficiently known by 

 the botanists. 



We placed the plants, c. 60 cm. in length, in a cylinder-glass in a 

 room with a temperature somewhat lower than the normal 18° G. Towards 

 winter the leaves were decaying and sunk to the bottom, while the 

 stems kept green. In January all the leaves were putrified. The stems 

 still kept green and were spun over by Beggiatoas. In March axillar 

 shoots began to grow forth, and we then placed some shoots in a glass 

 together with a great infecting material of Cladochytrium, whose infecting 

 power is at its full in this and the following month. On the first of May the 



