108 EVANS—EFFECT OF ENVIRONMENT ON THE 
months from the date of germination, there only remained an 
almost indistinguishable brown thread, in the midst of the 
functional roots, to mark its former position. It is interesting to 
note that the cotyledon was at that time still quite green, and as 
yet showed no signs of decay ; it remained an active assimilating 
organ for a considerable period after the total disappearance of 
the hypocotyl. 
My next step was to ascertain the environmental conditions 
under which the species grew, in case this might throw some 
light on the use of such an expansion of the embryonal axis to 
the plant. 
Luzula purpurea, Link., is a native of the Canary Islands 
and Madeira, and according to Buchenau (2) its habitat is in 
shady, moist places in rock clefts in wooded valleys; he also 
states that it is the only known annual species of the genus. 
The surroundings of the plant would therefore appear to be 
very similar to those in which such of our British luzulas as 
L. maxima, DC.,and L. vernalis, DC., are usually met with. For 
this reason it seemed likely that, in these species also, a similar 
development might be found to occur. I was, however, only 
able to obtain a small supply of seeds of ZL. maxima, DC., and of 
L. campestris, DC. Some of the seed was in each case sown 
upon the surface, some under about a quarter of an inch, of soil. 
In both cases the same results were observed as in the case of L. 
purpurea, Link., already described, with the exception that the 
germination below ground was much poorer in the case of 
the two British species. The experience of Mr. L. Stewart, at 
present Foreman of the Glass Department in the Royal Botanic 
Garden here, agrees with mine in this respect, for he informs 
me that L. purpurea, Link., is more easily raised from seed sown 
below the soil than is any other species of Luzuda he has 
knowledge of. 
I had now satisfied myself that the case of L. purpurea 
Link., was no exception to the general rule, and that the 
behaviour of its hypocotyl was not caused by the fact that it 
was an annual, but must have to do with the environment 
which the genus, as a whole, tends to favour. The seeds of a 
plant growing in a shady, wooded situation, where the soil is 
very loose and the leaf-fall great, must tend to become more 
