312 Trow. — Observations on Pythium nltimum , n. sp . 
EXPLANATION OF THE FIGURES IN PLATES 
XV AND XVI. 
Illustrating Dr. Trow’s paper on Pythium ultimum , n. sp. 
All the figures we’re drawn with the help of the camera lucida. Figs. 1-5 are 
representations of living material, the remaining ones are drawings of stained 
sections. Those of the first set are magnified about 550, of the second about 1250 
diameters. All the sections were 5 ^ thick. Median sections, i. e. the middle 
ones of series, are shown with one exception, viz. Fig. 16. 
Fig. 1. Structure and germination of an intercalary conidium. 
Fig. 2. Structure and germination of a terminal conidium. 
Fig. 3. Stages in the development of an oogonium and antheridium. 
Fig. 4. Further stages in the development of an oogonium and antheridium. 
Fertilization. 
Fig. 5. Stages in the maturation of an oospore. 
Figs. 6-32. Approximately successive stages in the development of the game- 
tangia, in fertilization, and in the maturation of the oospores. Pull description in 
the text. 
Figs. 33-40. Successive stages in the germination of the oospores, the fate of 
the reserve globule being neglected. The wall of the oogonium is represented in 
Figs. 38-40. 
Figs. 41-45. Successive stages in the germination of the oospores, the fate of 
the reserve globule being followed. The wall of the oogonium is represented in 
Fig- 43-45* 
Fig. 46. Young conidium fixed in Hermann’s solution. 
Fig. 47. Month-old conidium fixed by immersion in Flemming’s stronger solution 
for one hour, too short a time to secure good results. 
Figs. 48 and 49. Conidia fixed in chromacetic acid while germinating. Chromic 
acid .7 % , Acetic acid .3 %• 
