NOTES. 
APOSPORY IN PTERIS AQUILINA.— While at Squam 
Lake, New Hampshire, in July 1887, I noticed by the side of the 
road a plant of Pteris aquilina that presented a peculiar appearance 
which I, at first, thought must be due to the excessive heat then pre- 
vailing. Some of the pinnae w r ere normal, but others were curled 
and irregular in shape with the margins somewhat thickened. I had 
no microscope with me at the time, and it was not until my return 
to Cambridge that I recognized that the sporangia on the abnormal 
pinnae had developed in a peculiar manner, 
and that the present case was one of apo- 
spory, although not so well marked as 
similar cases described by Druery and 
Bower. As cases of apospory are not very 
common, an account of the peculiarities 
of the Pteris from Squam Lake may be of 
interest. 
In the first place, an examination of the 
normal pinnae showed that the formation 
of sporangia had scarcely begun, and on 
none of them had the sporangia advanced 
so far as the formation of the archesporium. 
The appearance of the abnormal pinnae is 
shown in Fig. 17. A few of the sporangia 
on the abnormal pinnae were nearly mature 
and contained perfectly formed spores ; but 
the greater part of the sporangia had, after 
the formation of the archesporium, de- 
veloped abnormally. In some cases the 
normal development had ceased even 
before that stage was reached, and what 
should have been sporangia had developed 
into sterile growths resembling, in some cases, moss-protonemata, in 
others, irregularly shaped prothalli. It should be remarked that the 
abnormal pinnae were most abundant at the tips of the different 
divisions of the frond, and the sporangia became more and more 
irregular the nearer they were to the tip. 
In the majority of cases, immediately after the formation of the arche- 
Fig, 17- 
