7 i6 



SCIENTIFIC RECREATIONS. 



The Entozoa or "intestinal" worms claim a brief notice at our hands^ 

 The entozoa are those beings which inhabit, as parasites, the intestines and 

 other parts of animals. Their history is still obscure, but there seems to be 

 about twenty varieties of these creatures, and a great number of animals 

 have their peculiar entozoa. The best known in the human subject are 

 the " Ascaris " or threadr-worm, the " Lumbricus Teres " or long- worm, and 

 the " Tamia " or tape-worm ; this last is jointed, and grows to several yards 

 in length. 



The development of these Taenia is one of the most curious perform- 

 ances of nature. Each of the joints shown in the illustration below 

 (fig. 842) is a perfected and mature proglottis, containing the ova or eggs, 

 which can only be brought to perfection when swallowed by a warm-blooded 

 animal (not the same from which they emanated). The head within the 



Fig. 842. Tape worm (proglottides). 



embryo then holds to the tissues and penetrates to the alimentary canal,, 

 where only it can redevelop joints from the so-called head, which has no- 

 organs and merely pushes out immature joints which are continued, and 

 they become more mature the farther they are pushed out by the new ones. 

 The " measles " of the pig are produced by the ova of these worms. 



MYRIAPODA. 



The "many-footed" annulosa include the centipedes and millipedes, and 

 may be regarded as a connecting link between the worms and the insects. 

 The heads of these animals are distinct from the body. 



The millipedes can be any day found under a large stone in a field 

 which has not been tilled, or any place where a stone has been suffered to 

 remain for some time undisturbed. These specimens are of the pill- 

 millipede order, because they roll themselves up into a ball when disturbed. 

 The myriapods of this country are not of large dimensions, but in tropical 

 climates they attain a great size. The giant centipede has been found in 

 South America more than a foot long, and is capable of inflicting severe 

 wounds, its tenacity being extraordinary and equalling that of the bull-dog 

 when once it has gripped its enemy. 



The myriapods have no wings ; they possess antennae, and numerous,. 



