256 : | Mr. CARLISLE' Obfervations 
Another mode of increafe allowed to Tenia (if we may call it 
increafe) is by an addition to the number of their joints. If we con- 
fider the individual joints as diftinét beings, it is fo ; and when we 
refle& upon the power of generation given to each joint, it makes 
this conjecture the more probable. We can hardly fuppofe that 
an ovum of a Tania, which at its full growth is thirty feet long, 
and compofed of four hundred joints, contained a young Tena 
compofed of this number of pieces; but I have feen young Tenia: 
not half a foot long, and not poffeffed of fifty joints, and ftill were 
éntire worms. We have alío many reafons to believe, that when 
a part of this animalis broken off from the reft, it is capable of 
forming a head for itfelf, and becomes an independent being. The 
fimple conftruétion of the head makes its regeneration a much _ 
more eafy operation than that of the tails and feet of lizards, 
which are compofed of bones and complicated veffels ; but this laft 
operation has been proved by the experiments of Spallanzani and 
many other naturaliíts. 
I have feen a disjoined part of a Tenia, one of whofe extremities 
had begun to put on the appearance of a head; the extyeme joint 
had become rounded, and the broken end had affumed the form 
of a deep cup, of which the margin was platted in a radiated man- 
ner, and the furface of the torn ftump was much fmaller than it 
muft have appeared when firft broken: Thefe circumftances cor- 
. roborate the opinion of this fecond mode of increafe, and indeed 
fomething very analogous is evident both in hydatids and in many 
vegetables. In Dr. Hunter's collection there are hydatids which 
= are found in cyfts of the liver, on whofe internal furface are vifible 
_a number of {mall pearl-like veficles, which are attached to it; this 
feems to be the mode of increafe peculiar to thefe bodies. Chains 
of individuals having a mutual connection are very common in 
. the vegetable kingdom: the common Mentha has a running root, 
which 
