298 PROCEEDINGS OF THE AMERICAN ACADEMY. 



tion, a terminal portion of an erect hypha is distinguished by a septum 

 from the portion below. Immediately beneath this septum is produced 

 ft branch which, growing upward, recurves to meet the side of the slend6r 

 zygophoric filament cut off by the septum already mentioned (Plate I, 

 Figure 1). The two zygophores are from the beginning unlike in 

 character as well as in origin. While the first, which contains but a 

 small amount of protoplasm that becomes massed at the point of contact 

 with the other, undergoes no further development, the second, which has 

 arisen immediately below it, is from the outset richly supplied with 

 dense protoplasm. Immediately after contact a progamete is developed 

 as a perpendicular outgrowth from the slender erect zygophore, and in 

 juxtaposition to this a progamete is formed by the terminal enlargement 

 of the more vigorous zygophoric branch (Figures 2 and 3). In each of 

 these progametes a transverse septum is formed, distinguishing the 

 gametes which are unequal in size, the larger being formed on the side 

 of the vegetatively more vigorous zygophore (Figures 4 and 5). This 

 difference in size is always distinct, though in some cases (Figure 6), 

 less marked than in others. The contents of the two gametes become 

 united through the disappearance of the intervening wall, and the 

 zygote here formed (Figure 7), by the gradual enlargement of the two 

 cells thus united, assumes the shape of a mature zygospore (Figure 8). 

 The supply of nutrient for this ripening process comes almost entirely 

 by way of the more vigorous zygophoric branch, and, although the 

 stretched wall of the larger gamete makes up the greater part of 

 the outline of the zygospore, still the stretched wall of the smaller 

 contril)utes to it. Although it may show a certain tendency in this 

 direction, the condition here is thus not comparable to an oogamous 

 fertilization where the male gamete furnishes protoplasm to, but forms 

 itself no essential part of, the mature oospore. There are neither cyto- 

 logical nor physiological data which will enable us to say with any degree 

 of certainty which of these two unequal gametes is to be considered male 

 in character, yet from the condition in oogamous Phycomycetes, it would 

 be natural to assume that the male is represented by the smaller of the 

 two uniting cells. The inequality in the size of the gametes is associated 

 with a still greater inequality in their suspensors ; while the suspensor 

 subtending the larger is always swollen, a suspensor is seldom ever 

 formed on the side of the smaller, since the septum which distinguishes 

 the gamete just mentioned is usually directly continuous with the wall 

 of the zygophoric filament. The mature zygospore thus appears to be 

 borne terminally by the swollen suspensor and merely appressed against 



