ao 
80 EQUISETUMS AND CALAMITES. 
Williamson, and shall try and point out that some of his observations 
will bear a second interpretation; and further, I believe that the 
Calamites do not differ so much in their essential characters from the 
living Equisetums as Prof. Willi i 
ga 
the spores. Unfortunately the reproduction is unknown in certain 
of the forms (Lycopodium, Phylloglossum, Psilotum, Tmesipteris), so 
that the remarks made do not apply to then erns, 
Equisetums, and Ophioglossacee: only one kind of spore exists, while 
zocarps and Lycopods (except the fourg just mentioned) 
two kinds are formed, the macrospores forming a more or less rudi- 
mentary prothallus with one or more archegonia, while the microspores 
form a very minute or imperfect prothallus with an antheridial cell 
which forms numerous spermatozoids. Leaving out of view the 
~ 
Vike Ot eee 
ae 
rated from the Ferns, as they possess v i 
the known cases the prothallus is not green and is produced under- — 
" See Sachs’ ‘* Lehrbuch” (2 ed.), p. 345, et seq. 
+ Monececious prothalli are only exceptional, according to Hofmeister. 
