81 
many of them may be considered as intermediate between those 
of 5. alterniflora and S. stricta , although they are frequently, 
more or less, obscured by the remarkable readiness with which 
Townsend’s Spartina responds to external conditions, now dwarf¬ 
ing down to the modest size of S. stricta , now running up to 
and even exceeding the height of fine examples of S. alterniflora. 
Similarly, its remarkable vigour, its pronounced instability, and 
its varying fertility, very much enhanced in certain years and 
almost suppressed in others, may be adduced in favour of the 
hybrid nature of the grass, as those conditions are traits frequently 
observed in hybrids. But the strongest evidence seems to be in 
the following fact:— Spartina alterniflora and S. stricta meet out¬ 
side their English area only in one other place, namely, the 
estuary of the Bidassoa River, South of Bayonne, in the Bay ol 
Biscay. There they grow intermixed, and among them has been 
found their hybrid. Foucaud described it in 1895, and named it 
Spartina Neyrautii , after its discoverer, Neyraut. Now this 
S'. Neyrautii is so similar to S. Townsendii that Foucaud pro¬ 
claimed both as hybrids from the same parents, explaining such 
differences as there are by the assumption that S. alterniflora was 
the female parent in the case of the Bidassoa cross, and S. stricta 
in that of the English plant. The fact is very remarkable, and 
the argument deducible from it for the hybrid origin of Towns¬ 
end’s grass has almost the force of experimental proof. 
Thanks to its vigour and occasional fertility, Townsend’s 
grass has, in a comparatively short time, conquered thousands of 
acres of bare mud-land, it has invaded and, in places, much 
reduced the beds of Spartina alterniflora in Southampton Water, 
and even attacked the marshes which so far have been the home 
of Spartina stricta. However, its principal domain is and will 
probably for ever be the mudflats from one to three feet below 
high water-mark. Here the changes brought about by Towns¬ 
end's grass are remarkable. It is not only that the aspect of 
the flats is altered, the eye meeting great expanses of green com¬ 
parable to meadows or cornfields, where there was previously a 
monotonous sheet of grey at low- and half-tide, also the animal 
life on the flats and their physical character is undergoing a 
change. To mention only a few economically interesting effects 
on the fauna : in more than one place the larger molluscs which 
were collected for food have disappeared ; with the arrival of the 
grass, eel-spearing has been seriously interfered with, whilst even 
duck shooting has been spoiled owing to the birds finding a 
welcome cover in the dense grass belts. But the most important 
change concerns the physical conditions of the flats. It is obvious 
that the copious systems of roots and stolons must contribute 
to the stabilisation and solidification of the mud. In addition to 
this binding action the stems and lower leaves and leaf-bases 
act as a very effective strainer on the water, which is charged 
with solid particles brought down by the streams, catching and 
precipitating them. The result is an accelerated and increased 
p 
