Miscellaneous. 437 



destitute of internal organs, but the embryogenic development of these 

 organisms is still too little known to permit us to arrive at any cer- 

 tain conclusion. 



The division of Nematelmia includes among its members a worm 

 with an elongated, cylindrical body, resembling a brown horse-hair. Its 

 coriaceous skin readily absorbs the liquid which surrounds it. When 

 dried, its body becomes as brittle as a horny thread. This worm, known 

 by the name of Gordius, inhabits the water of springs, ditches, Sec. 

 Till en taken from the water, it retains its life for a certain time, and 

 on being restored to that element resumes its usual movements. This 

 property is very useful to it during a certain period of its life. The 

 Gordius does not, as was long supposed, inhabit water only, but 

 passes the first portion of its life as a parasite in the bodies of various 

 insects, and especially in the abdominal cavity of grasshoppers, where 

 this worm, so large when compared with its habitation, may be found 

 rolled up into a ball. When its sexual organs are developed, it quits 

 its first habitation to finish its career in some piece of water, or in the 

 basin of some rustic spring, where it deposits its eggs in long chains. 



We are still ignorant of the first stage in the development of the 

 Ascarides, which are very common in the human intestines. It is 

 known, however, that as soon as their eggs are mature, these worms 

 quit their ordinary habitation and sometimes even perforate the in- 

 testinal canal. Some observations made on a parasite of the frog, 

 serve not only to throw some light on the development of the Asca- 

 rides, but also on the presence of worms in the closed cavities of the 

 bodies of animals. Certain Nematoid worms deposit their young in 

 the blood-vessels of frogs. These little parasites, which are true 

 larvfe, circulate during a certain time with the blood, until, having 

 arrived at the proper period of their development, they pierce the 

 walls of the capillary vessels. After secreting a capsule, which at 

 first is colourless, but afterwards becomes brown, the worm rolls itself 

 up spirally within it. When transparent portions of the mesentery of 

 a frog are examined under the microscope, these little capsules may 

 frequently be seen, always arranged along the course of the blood- 

 vessels. The worm in this pupa state does not possess generative 

 organs ; these are not developed until after it has left the capsule. 

 Sometimes the young worm, not finding the conditions necessary for 

 its further development, dies while still in the capsule, which then 

 becomes incrusted with calcareous matter, and remains in the midst 

 of the animal tissues in the form of a small stony concretion. A 

 great number of individuals of a worm of this group {Trichina spi- 

 ralis), which presents these calcareous incrustations, has recently 

 been discovered in the muscles of the human body. 



Every one knows the Tcenia, or tapeworm, which frequently attains 

 an enormous length in the human intestines. Every one of its nu- 

 merous segments is filled with ovaries and testicles. At the period 

 when the eggs contained in the ovaries become mature, some of the 

 segments, either separated or attached to one another, become de- 

 tached and pass from the body with the excrements. It is not yet 

 known how the young tapeworms, thus dispersed, arrive in situations 

 favourable to their development, nevertheless the repartition of the 



