NOTE, 
NOTE ON THE DURATION OF THE PROTHALLIA OF LASTRAEA 
FILIX-MAS, PRESL. — I venture to record here some observations on prothallia of 
Lastraea Filix-mas , which seem to indicate a greater vitality and more prolonged 
duration than have been generally attributed to prothallia. 
In August, 1912 , 1 desired to obtain some early stages of fern prothallia for class 
purposes. To this end, I used a tank with a glass front, and covered the bottom with 
pieces of coke partly immersed in water. On these were laid some mature fronds of 
Lastraea , and the top covered over with slate slabs. The conditions for germination seem 
to have been successfully met, and by early October the pieces of coke were covered by 
myriads of prothallia in all the early stages of development. 
These were in due course used for demonstration purposes, and the tank 
dismantled. I retained, however, two or three pieces of the coke, and placed them in 
a glass basin with water, and covered the top with a glass plate. The basin was then 
placed on a shelf in the laboratory and for some time forgotten. 
It was not until March, 1914, after an interval of about twenty months from the 
sowing of the spores, that I remembered about these prothallia, and re-examined them. 
Fortunately the water had not dried up, thanks to the circumstance that the edge of the 
basin was ground, and the covering plate fitted fairly closely. 
The appearance then presented by the contents of the basin was so remarkable, 
that at the first glance I supposed that the crop of prothallia had been succeeded by 
a crop of moss. For in the feeble illumination of the shelf, each prothallium had 
grown vertically upwards, covering the flanks of the coke lumps as thickly as they 
could stand, and resembling miniature forests on the sloping surfaces. The average 
height was about 15 millimetres, and the breadth from 1 millimetre to i-|. From the 
surface turned away from the light (invariably the morphologically under surface) in- 
numerable rhizoids attached the vertical prothallia like guy-ropes to the surface of the 
coke, and the edges bristled with the characteristic mucilage cells. While the prothallia 
were light green through the greater part of their length, the bases were brown through 
the death of the cells. I could find no fungi, however, on the decadent portion. 
On microscopic examination, I could find no trace of archegonia on any of these 
depauperated prothallia, but the whole of the under surface was studded over with 
antheridia, to the number of many hundreds on each. Near the apex were immature 
antheridia, then farther back antheridia which released the antherozoids on access 
of water, and in the older parts antheridia which had dehisced. I calculated that upon 
the one prothallium on which I attempted a count, there must have been from 700 to 
1,000 antheridia from base to apex. 
I now transplanted some of these prothallia, laying them flat with the under surface 
downwards, on suitable soil in an earthenware saucer, and placed them under a bell- 
[Annals of Botany, Vol. XXXIII. No. CXXX. April, 1919.] 
