370 
POPULAR SCIENCE REVIEW. 
being a quick motion of the body through the water — undis- 
tinguishable in fact from that of some of the lower forms of 
animal life — continuing for a period varying from half an hour 
to several hours, at the expiration of which they settle down, 
reassume the characters of ordinary vegetable cells, lose their 
cilia, and give rise, by cell-division, to new individuals resem- 
bling the parent-plant. Those zoospores which are furnished 
with cilia at one extremity only, direct that extremity, which 
is destitute of chlorophyll or green colouring matter, towards 
the light. Closely resembling these zoospores are the “ sperma- 
tozoa ” of the higher orders of cryptogamic plants, ferns, equise- 
tums, and mosses. These bodies (fig. 6) are produced in the 
antheridia or male organs, again by a modification of the 
protoplasmic cell-contents ; they are filiform bodies of various 
forms, mostly presenting one or more spiral curves, and fur- 
nished with vibratile cilia. When released from the parent 
cells, they move about with great activity until they come 
into contact with the opening of the archegonium or female 
organ, which they enter, and thus fructify the germ of the new 
plant. Pringsheim describes the process by which the sperma- 
tozoa enter the archegonium as a very peculiar twisting motion r 
due to the action of the mucus or protoplasm of the germ-cell. 
He has seen a large number of spermatozoa enter a single cell, 
forming a kind of chain. 
In describing these curious bodies, of the convection of 
which with the vegetable kingdom there is no room for doubt, 
one is irresistibly reminded of these lowly forms of animal life 
known as Amoeba and Gromia , consisting apparently of shape- 
less masses of protoplasm, possessing indeed far more restricted 
powers of locomotion than the zoospores and spermatozoa, their 
faculties in this respect being confined to the protrusion and 
retractation of arms or pseudopodia, by means of which a slow 
movement is effected. If the possession of consciousness and 
of a voluntary control over the movements of the body belongs 
to the animal kingdom even to its lowest forms, it is difficult 
to frame any cogent reason for denying these faculties to the 
vegetable organisms which we have been considering. A very 
interesting problem also presents itself for solution in the almost 
perfect identity of constitution between these lowest forms of 
animals and the protoplasmic elements in the constitution of 
more highly organised forms. If the Amoebae and Gromice are 
admitted to be distinct individual animals, the same line of 
reasoning would almost compel us to admit to the same rank 
the white corpuscles of the blood of mammalia, which present 
almost the same characters and possess the same power of pro- 
trusion and retractation of a portion of their substance. 
The instances above cited illustrate the faculty of spon- 
