126 ASCOMYCETES AND RHODOPHYCE, 
Lastly, the development of the gonemoblast filaments in such forms 
as Batrachospermum and Nemad/ion is certainly paralleled in the 
ascogenous hyphe of Hryszphe, and for the same reason we may look 
upon the ascogenous hyphe of Pyroxema and Ascobolus as homolo- 
gous with the sporogenous filaments of Dasya and Dudresnya. The 
ascogenous hyphe obtain food later in their development from con- 
tiguous vegetative cells existing chiefly for that purpose. In this case 
a cytoplasmic fusion is not necessary for the purpose of nutrition, 
although it may possibly occur, but in the Rhodophycee, because of 
their aquatic habit, the sporogenous filaments must fuse with the brood 
cells in order to obtain nourishment from them in the most effective way. 
This view of phylogenetic relationship is made more probable by 
the researches of Thaxter on the Laboulbentacee, in which certain 
representatives are shown to be transitional between the Florzdee and 
the Ascomycetes. It is certain that the Ascomycetes resemble the red 
alge more than they do the lower fungi, yet, as we may conclude with 
Harper, ‘‘ whether these resemblances are the result of blood relation- 
ship or merely due to that similarity in the chemical constitution of 
the protoplasm of different organisms, which under similar conditions 
enables it to develop structures nearly related in appearance out of 
rudiments which may be extremely diverse, is likely to remain a 
puzzling question.” 
COLLEMA. 
The much discredited doctrine of Stahl (’77) and others concerning 
sexuality in certain lichens has received fresh confirmation recently by 
the researches of Baur (’98) and Darbyshire (’99). Although neither 
cell nor nuclear fusion has been established beyond all doubt, yet the 
morphological value of the sexual organs can not be very well ques- 
tioned. 
According to Stahl, as is well known, the sexual organs of Collema 
microphyllum occur in large numbers especially upon the illuminated 
edges of the rapidly growing vegetative lobes of the thallus. The 
carpogonium arises some little distance beneath the upper surface of 
the thallus as an ordinary hyphal branch. The lower part, the asco- 
gonium, consists of a row of short cells coiled up somewhat in the 
form of a corkscrew, which are distinguished from the other hyphal 
cells by their larger diameter and denser plasmic contents (Fig. 50, A). 
The number of cells composing the ascogonium, which makes two or 
three turns, varies considerably, but may often reach twelve. The 
ascogonium is continued into a straight filament, the trichogyne, which 
extends to the upper surface of the thallus, The cells of the tricho- 
