Philosophical Transactions. 387 
° / Mt 
Longitude of Point de Galle Flagstaff . 80 17.2 .E 
Latitude of ditto bs i ; 6 050 N. 
Longitude of the Friar’s Hood : : 81 36 31 E. 
Latitude of ditto d : ‘ : 7 29 35 - N. 
Longitude of Canton - f : SPs es laa 
14. Observations on the Genus Planaria. By J. R. Johnson, 
M.D., F.R.S. 
This paper describes the habits of several species of the 
above singular and extensive genus. The planarie are little 
animals, found in slow streams, usually clustered together, and 
attached to the roots and leaves of aquatic plants, or to pieces 
of wood, &c. When at rest, they appear spherical ; when in 
motion, linear ; they move sometimes like the snail, and some-= 
times like the leech. Their anatomy is with difficulty made 
out, but the body appears to consist of one common cavity, 
with diverging cells, like that of the medicinal leech. They 
have two circular ventral apertures, the lower one -con-= 
ducting to the ovarium; the uppermost giving passage to a 
long flexible tube, the use of which Dr. Johnson discovered by 
accidert. Being desirous of ascertaining their proper food, he 
threw among them several aquatic insects and worms; pre- 
sently one of them projected his tube, and firmly affixed it to 
the worm ; other planarie now came to his assistance, and all 
the writhings of the worm were inadequate to his disentangle- 
ment. They seized upon dead worms in the same way, and 
while thus affixed, their heads and mouths appeared unoccu- 
pied, which induced our author to suspect that they might re- 
ceive nourishment by the tube. To determine this point, he 
cut the head off one of the planariz, and a day or two after 
the headless body affixed itself by the tube to a worm, and 
became as before, distended with food, thus affording indispu- 
table proof of nourishment having been taken by the tubular 
organ only. When, however, this tubular organ is injured, or 
removed, they then take sustenance by the mouth. 
Dr. Johnson has ascertained that some of the species of 
planariz are oviparous ; these animals have, however, another 
method of perpetuating their species, namely, by a natural 
division of the body into two portions, the head part reproduc- 
ing a tail, and the tail a head, in about fourteen or more days, 
depending upon the state of the atmosphere. ‘The author de- 
‘tails a number of experiments, illustrating this reproduction 
after artificial division, To render these successful, the pla- 
narize should be divided immediately on being taken from their 
native haunts, for confinement renders them sickly and in- 
active. 
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