1910] TWISS—PROTHALLIA OF ANEIMIA AND LYGODIUM 177 
spines and a general delicate coat of protoplasm. The exine is a 
coat of two differently staining portions and with ridges on its outer 
surface. The intine is first clearly seen at the same stage as 
in Lygodium, when the exine differentiates into red and yellow 
portions. 
FORMATION OF THE THALLUS 
The main work was done with Aneimia Phyllitidis (L.) Sw., 
which Dr. Barngs kindly sent from Mexico at the time of his botani- 
cal expedition there in 1908. Younger stages were obtained from 
spores of A. hirsuta from material sent to Dr.‘ CHAMBERLAIN from 
the Philippine Islands, and from those of A. Phyllitidis, which Dr. 
TRELEASE was kind enough to send from the Missouri Botanical 
Gardens. Spores were also received from Dr. Britton from the 
New York Botanical Garden, but cultures from these were not 
successful. For the identification of the specimens I am indebted 
to Dr. Jesse M. GrEEMAN of the Field Museum of Natural History, 
Chicago. 
Germination is somewhat slower than in Lygodium and does not 
take place till the seventeenth or nineteenth day. The rhizoid is first 
to protrude and the first prothallial cell follows, but the small cell 
between them does not emerge as it does in Lygodium. It is only 
when the filament and rhizoid have attained considerable length that 
it can be seen at all (fig. 32). 
The filament does not broaden so early or in so regular a manner 
as in Lygodium. A spatulate and often irregular thallus is formed 
(figs. 34, 35), and within about ten days initials appear at the side 
(fig. 36). From the rapid division of these initials the thallus takes on 
the heart-shaped form, the lobes being unequal in size. In this case the 
larger lobe is the original thallus and the smaller lobe is the younger, 
as GOEBEL reports for Pteris (11, p. 205). In prothallia hitherto 
Studied, this inequality is reported as persistent, but while this was 
true of A. hirsuta, it was not for A. Phyllitidis, the lobes of this species 
finally becoming of equal size, as they do in Lygodium. ‘There is 
here further reason for agreeing with GorBEL (II, p. 205) when he 
says, “I do not believe that one can construct a phyletic relationship 
between apical and lateral position of meristem; . . . - in different 
sections of the Filicineae both occur.” 
