102 ZOOLOGNX 
The question whether the proglottides which are cast off 
one by one by the tapeworm should be regarded as individuals, 
is one which has given rise to much difference of opinion. 
The comparison which has been instituted between a single 
proglottis and the body of a Trematode gives some support to 
the view that the scolex produces by strobilisation a number 
of individuals (the proglottides), which in their turn reproduce 
sexually. If this view be retained, the Taeniidae exhibit a 
well-marked alternation of generations. 
On the other hand, the nervous, excretory, and to some 
extent the muscular systems are common to all, and the 
detached proglottides are not capable of individual life or 
Fic. 69.—Various forms of 'Tape- Worms. 
A. Tuenia echinococcus. x 12. From Leuckart. 
B. Archigetes Sieboldii. x 60. From Leuckart. 
C. Echinobothrium typus. * 10. From Van Beneden, 
D. Caryophyllaeus mutabilis. x about 5. From Carus. 
maintenance. It is true that they are stated to increase in 
size when separated, but this may be due to imbibition of 
fluids, and it is doubtful how far it corresponds with growth. 
