420 ` A Speculation on Protoplasm. [July, ° 
nearly pure silica; so also are the minute barbs upon the awns; 
and the short bristles on the surface of the ovaries in Erodium 
resemble, in miniature, the spiny bones in the dorsal fin of a 
erch 
Other bearded or barbed-seeded or rough-burred plants have 
increased in several places within the region referred to in this 
paper, among these are the burr-clover (Medicago denticulata) and 
the thistles (Centaurea melitensis L., and C. solstialis L.), both 
introduced species; the barley-grass, however, has the advantage 
over all others and is likely to maintain it. 
A SPECULATION ON PROTOPLASM. 
BY PERSIFOR FRAZER, JR. 
Ape researches of comparative anatomists in late years have 
thrown much light upon the mode of development of the 
germ or embryo to the adult form of the species from which 
it is derived, and by the labors of Haeckel, Huxley, Cope, and 
others, much encouragement has been offered to the hope that 
man will yet push his knowledge of the processes of the devel- 
opment of life at least so far into their infinitesimal begin- 
nings that the highest powers of the microscope and the most 
delicate appliances of physical science can no longer aid him. In 
this gradual triumph over what at- first seemed insurmountable 
difficulties, many lines of interesting speculation are opened up, 
which, though lacking the permanent value of demonstration, are 
not without a certain use. 
One of these is connected with the material out of which these oe 
wonderful structures are built; a material seeming to form the 
common point of intersection of all lines of organisms. For the 
latter, though widely separated in their several states of perfect 
development, when traced towards their origin, exhibit more and 
more striking resemblances and analogies ; and they consist of a 
common substance, namely, the ultimately structureless (oF 
amorphous as it is sometimes perhaps too ae eral pro- 
ERE or PETES 
