Notes. 
158 
of November, 1895, upon a carefully sterilized soil, consisting of 
a mixture of vegetable mould and sand. The pot was kept con- 
stantly covered with a glass plate, and the necessity of watering 
was avoided by standing the pot in a large saucer kept full of water. 
A close crop of well-formed prothalli, on which antheridia and 
archegonia were present, completely covered the surface of the soil. 
In April, 1896; a number of the prothalli bore normal embryos 
in an early stage of development. Three months later numerous 
young plants were present, which were found on examination to be 
normally produced. 
The prothalli which had not been fertilized had lost the heart- 
shaped outline and elongated considerably ; some of them reached 
a length of 2 cm., and were 5 mm. in breadth. The archegonia 
were very numerous, and were situated upon a distinct cushion, which 
was continued in the larger prothalli as a well-marked midrib. They 
were arranged in transverse rows ; their necks had opened in a 
normal manner, and the canal showed the usual brown discoloration. 
Antheridia were present on some of the prothalli. 
In some of these prothalli the midrib was continued into a cylin- 
drical process of variable thickness. This arose in some examples as 
a direct continuation of the apex, but more frequently was attached 
to the under surface, just behind the apex of the prothallus ; in one 
instance it was found in a corresponding position on the upper surface. 
The actual apex usually loses its merismatic appearance ; it grows 
out as a narrow triangular lobe, which consists of colourless cells, and 
contains tracheides. This lobe closely resembles the ‘ middle lobe * 1 
found in the apogamous prothalli of certain Ferns, and probably 
corresponds to it. In a few instances this middle lobe is formed, but 
no cylindrical process arises; in such cases secondary prothalli are 
produced from the anterior margin of the thin lateral wings, and the 
whole closely resembles an aborting prothallus of Aspidium ftlix-mas 
or Pteris cretica. When the prothalli are seen from above, the 
anterior edge can be traced across the base of the cylindrical process. 
As will be’ described below, the first sporangia formed on the prothallus 
are usually situated on this margin, especially on the ‘ middle lobe/ 
The process is of the same deep green colour as the midrib. Sexual 
organs, often in considerable numbers, are borne upon it. They are 
1 Farlow, Quart. Journ. Microscop. Sc., 1874, p. 268. De Bary, Bot. Zeit., 
1878, p. 463. 
