316 Agricultural Experiment Station, Ithaca, N, Y. 



February, 1894-. Tlie affected protliallia were quite soft, limp, and 

 darker in color than the healthy ones. Some were placed in water 

 on a glass slip and kept in a moist chamber. The following day the 

 fungus had grown out of the prothallial tissue and had extended a 

 considerable distance over the slip. Tiie mycelium is at "first non 

 setate and contains granular protoplasm which is present in minute 

 irregular masses, having in the larger threads much the appearance 

 ■of the protoplasm in some raucors, and in some cases well marked 

 and strong currents of the protoplasm have been observed, which 

 Tesemble the movement of the protoplasm in these plants. 



The threads branch monopodially, the extent of the branching 

 depending, to a certain extent, on the amount of the vegetive 

 growth. The threads put out in the water from the prothallia may 

 "be quite long and possess primary and secondary branches before 

 conidia are developed to any great extent. The conidia are developed 

 at the ends of the main threads or their branches, the hypha swell- 

 ing at the end into a round body several titnes the diameter of the 

 thread itself. In other cases the thread may develop a conidium 

 while it is still quite short and the growth of the thread in length 

 practically cease. In other cases the conidia are developed at the 

 ends of the primary or secondary branches as well ae at the end of 

 the main hypha. Where the conditions are not favorable for the 

 rapid growth of the vegetative portion of the plant, sometimes the 

 conidia are developed more profusely and rapidly so that they are 

 many times produced in chains. Frequently these are in nearly 



Explanation of Plate 1. Artotrogus debaryanns (Hesse.) 



Figs. 1, 2 and 3, differeut stages in fertilization; aautheridium, oog. oogonium, 

 ■e. c. egg cell, gon. gonoplasm, oosj). oospore. 



Figs. 4 and 5 intercalary oogonium with stalk antheridium (s. a.) and branch 

 antheridium (6. a.) in 4 with gonoplasm separated from tho i^eiiplasm, and in 

 •5 fertilization complete. 



Fig. 6 terminal oogonium with stalk and branch antheridium. 



Figs. 7 and 8 different stages in development, and fertilization, of sexual 

 organs; b in 7, oogonium before the formation of the egg cell. 



Fig. 9 oogonium with stalk antheridium (a) which has fertilized the egg cell, 

 and branch antheridium (6) from another hypha than that which bears the 

 oogonium. In this branch antheridium the gonoplasm has separated, and the 

 fertilization tube has formed, but fertilization took place from the stalk anther- 

 idium first and the wall of the oospore prevented the use of the gonoplasm from 

 the branch antheridium. 



All the figures drawn with aid of camera lucida and magnified fifty times more 

 than the scale. Scale— 1 millimeter. 



