Remarks on the Natural order Cycadee. 45 
The first, second and third experiments indicate, in the tenth 
column of the preceding table, that beyond a certain limit the ratio 
of weight of metal to extracting force begins to diminish, showing 
that it would be more economical to increase the number rather than 
the length of the spikes, for producing a given effect in fastening 
materials together. In this case, also, it will be perceived, that the 
adhesion has a much closer relation to the areas of the compressing 
faces of the spikes, than to their weights. For three of the experi- 
ments this ratio may be regarded as identical, and dividing, for each 
of the five experiments, the observed retention by the area of the 
two faces opposed to the ends of the fibres, we get a mean result, 
which proves that the absolute retaining power of unseasoned chest- 
nut, on square or flat spikes of from 1.8 to 3.9 inches in length, is 
about 813 lbs. for every square inch of those faces which condense 
longitudinally the fibres of the timber. 
Art. 1V.—Remarks on the Natural order Cycadee, with a descrip- 
tion of the ovula and seeds of Cycas revoluta, Willd.; by A. J. 
Downine. 
[Read before the Lyceum of Natural History, New York, Oct. 17, 1836.] 
Cycas revoluta, figured in the accompanying plate, (Plate I.) be- 
longs to a genus comprising but four other known species, which to- 
gether with Zamia constitute the Cycadea, one of the smallest but 
most interesting orders in the whole vegetable kingdom. 'Their sin- 
’ gular structure and manner of growth, their simple cylindrical stems 
and crowning tufts of foliage, like some of the Palms, and their 
commonly gyrate vernation, like that of most Ferns, as well as their 
anomalous inflorescence and fructification, have rendered them ob- 
jects alike of the greatest interest and perplexity to the learned bot- 
anists who have examined them. 
Cycas circinalis, Willd., a native of Malabar and Japan, seems 
to have been the first species discovered, haying been described by 
Rheede, as early as 1682.* Rumphius,} in 1741, figured and de- 
scribed it under the name of Olus calappoides: he remarks its re- 
semblance to the arborescent Ferns, and thinks it might with pro- 
priety be called Osmunda arborescens. Linneus, who first gave the 
genus its present name, seems, from the imperfect manner in which 
its structure was known in his time, to have been greatly at a loss 
* Hort. Malab. vol. ii, p. 9. +t Herb. Amboiense, vol. i, p.87. 
