PARASITES OF MAN. 97 



PARASITES OF :M A N . * 



BY T. SPEXCER COBBOLD, M.D., F.R.S. 



[Continued from page 59.] 

 In continuing this record it is, perhaps, as well that I should remind 

 the members of the Section that the Cestodes differ essentially from the 

 Trematodes in that the so-called species are multiple in character. 

 What is spoken of as a tapeworm is not one creature, but in reality a 

 multitude of organisms, or zooids, arranged in single iile. The head 

 itself is merely the topmost zooid, modified in shape, and armed with 

 sucking disks, so as to form a means of anchorage for the whole colony. 

 This cephalic holdfast, as it might be called, is iu some sense the 

 counterpart of what we see not only in the fixed poh'pes, but also in the free 

 compound medusae. In caiTying out the analogy it must not be forgotten 

 that the solid hydrorhiza of an ordinary Sertularian polype was once a 

 free swimming ciliated larva, whilst the inflated end of the coenosarc 

 forming the float of Physalus had a similar origin. In all these cases 

 the metamorphosis of a larva, either directly or indirectly, secures the 

 formation of an organ of anchorage or support involving the welfare of 

 the entire chain or colonj' of zooids. It is sufiicient to insist upon the 

 strict analogy of these phenomena without suggesting questions of 

 homology. An ordinary human tapeworm (such, for example, as that 

 derived from eating measled beef) consists of about twelve hundred 

 zooids, or proglottides. Each proglottis is bisexual, and, when mature, 

 is capable of holding, according to Leuckai-t, about 35,000 eggs. The 

 entire colony of twelve hundred zooids is renewed every three months, 

 and thus it follows that the amount of egg-dispersion annually resulting 

 from a single beef-tapeworm cannot be less than twelve millions. In all 

 probability this calculation is very much below the mark, seeing that the 

 35,000 impregnated germs capable of existing in the fully mature pro- 

 glottis, at a given period, do not by any means serve to fix the limit of 

 the possibilities of egg-formation within the proglottis. Of course, as 

 compared with the quantitj' of germs distributed, the number that 

 Bur\'ive and come to perfection, as Tsenias, must be infinitesimally small. 



Cestoda. 

 13. — Tcenia viedioraneUatn, Kiichenmeister. 



Synonymy. — T. saginata, Goeze ; T. dentata, Nicolai ; T. inermis, 



Moquin-Tandon ; TceniorJnjnchus, Weinland. 

 Larva. — A simple Scolex, known as the beef measle, (Cysticercus 



bovis, Cobbold.) 

 Intermediate Host. — The Ox, (Bos taunis, ) and all its varieties. The 



cattle of the Punjab are largely infested. As many as 800 Cysticerci 



have been counted by Dr. Joseph Fleming iu a pound of flesh 



taken from the psoas muscles. 



* Eead before the Micrnscopical Section of the Birmingham Natural History and 

 Microscopical Society, March 19th, 1878. Mr. Hughes, en Dr. Cobbol.Vs behalf, 

 exhibited the following specimens :— The beef-tapeworm, (Tcenia mecliccnnellata,) 

 and its measle, (Ci/sticercus bovis,) the pork-tapc-woim, (T. solium,) and its measle 

 (Cyst, celliilnsa;.) from tbe hiaman brain; the sleid<r tapeworm. (T. tenella,) the 

 ridged tapeworm. (T. lophosoma,) the dwarf tapeworm from Egypt, ('!'. nana,) 

 and the elliptic tapeworm, (T. ellijptica.) 



