8 
Journal of Mycology 
[Vol. 10 
Fig. 12, Mature plant, zoospores escaping, sterile basal part limited by thin wall 
which is arched outward slightly because of the endosmotic pressure in the 
protoplast, and the removal of the pressure within the primary sporangium. 
Fig. 13, One individual of Harpochytrium attacked by another, the parasitic one only 
half the size and age of the host individual. 
Fig. 14, Later stage, showing degeneration of the host individual and the increased 
size of the parasitic individual. 
Fig. 15, Mature individual attached at the side a short distance from the base. 
Fig. 16, Mature individual attached at the end at a point between two adjacent 
Spirogyra cells. 
Fig. 17, Same plant with zoospores escaping. This plant was kept in cell culture 
and the secondary sporangium from the sterile basal part began to grow 
before the developed zoospores escaped, and was forced out slightly at one 
side. The apex of individuals in Figs. 15, 16, show the peculiar condition 
shortly before formation of zoospores. In Fig. 17, amoeboid movement of some 
zoospores shown in the sporangium and also escaping. 
Fig. 18, The zoospore after escaping from sporangium still showing amoeboid 
movement. 
Fig. 19, Five individuals showing stages in attachment and elongation of zoospores.. 
Figs. 6, 7, 11, 12, 13, 14, show the disk-like holdfast and absorbent disk be¬ 
tween the outer and inner lamellae of cell wall. 
Figs. 1-19 from specimens collected at Ithaca, N. Y. 
Fig. 24, after Dangeard. 
Harpochytrium htalothecae Lagerheim. 
Fig. 20, Showing two young individuals attached to cell of host (Hyalotheca dis- 
siliens), one of the zoospores still withm the slime and just having developed 
the slender stalk; the other individual, the zoospore having elongated and the 
outer end projecting beyond the slime sheath. 
Fig. 21, Mature individual attacked by a filamentous bacterium. 
Figs. 20, 21, from specimens collected at Ithaca, N. Y. 
Fig. 25, after Gobi. 
Fig. 26, after Lagerheim. 
Harpochytrium intermedium Atkinson. 
Fig. 22, Half grown individual attached to Conferva utriculosa, showing disk-like 
haustorium between outer and inner lamellae of cell wall. 
Fig. 23, Mature individual with empty primary sporangium, and young secondary 
sporangium developing. 
Figs. 22, 23, from material collected at Ithaca, N. Y. 
CULTURES OF UREDINEAE IN 1903. 1 
J. C. ARTHUR. 
The present article forms the fourth of a series of reports 2 
by the author upon the cultures of plant rusts. They cover the 
years from 1899 to the present inclusive. This report is devoted 
both to autoecious and heteroecious species, among which the 
grass and sedge rusts have had a prominent place. The number 
of species studied and the number of cultures made have fallen 
off somewhat from last year, partly because it was late in the 
spring before assistance was secured to carry on the work, and 
partly because a less number of collections of teleutospores and 
field observations were obtained upon which to base the work. 
The results however, fully equal in interest and importance those 
of last year, or possibly exceed them. 
The expense of additional assistance in carrying on the 
work, and to some extent the expense of procuring material, was 
1 Read before the Botanical Society of America, St, Louis, December 
30, 1903. 
2 See Bot. Gaz. ^9:268-276; Jour. Mycol. 5:51-56; and Bot. Gaz. 
55:10-23. 
