51 



intended to have followed the same line of argument in liis future address. The 

 concluding suggestion of Mr. Draper to form a collection of drawings of appear- 

 ances as observed by the Microscopist, for the purpose of adding to the coUec- 

 tion of the Club, he thought particularly valuable. 



Mr. F. Durham, in a few remarks explanatory of the specimens he exhibited, 

 said : Under this microscope, with an inch object-glass, is the head and part of 

 the body of a tape-worm from the intestines of a dog. The head is provided 

 with four suckers, and a double circle of very peculiar booklets, by which it is 

 firmly fixed to the interior of the intestine. This animal has neither mouth 

 nor ahmentary canal, but imbibes its food, already digested for it, through its 

 tissues. The body, a small portion of which is shown, is made up of an immense 

 number of similar segments, and in some species reaches a length of a dozen 

 feet or more. Each segment may be said to be a perfect animal, for each 

 possesses all the organs necessary for the production of a large number of ova. 

 These ova, which are little roundish vesicles with booklets, similar to those of 

 the mature animal, pass through a variety of changes before attaining matu- 

 rity. They are passed out from the bodies of their hosts, or the mature segment 

 full of them is so passed, with the excrement. The ova are thus distributed over 

 the country. Of course, happily, immense numbers perish; but many, in a 

 variety of ways, get into the intestines of other animals. Thus they may be 

 drank with water, or in the case of herbivorous animals, eaten with the food. 

 It is only, however, in the intestines of some animals that they become at once 

 developed into tape-worms ; in others they pass from the intestines, either being 

 carried by the circulation, or boring their way through the tissues until they 

 reach a suitable spot. 



The liver appears a very favourite place. In this organ one of these larvjB (as 

 we wiU call them) may attach itself by its hooklets, and begin to grow. Its 

 body swells and swells until it forms an immense sac, filled with fluid. At the 

 same time there are developed, both inside and outside it, other similar little 

 animals, which also grow in the same way, and inside them again others may 

 be found. 



Various diseased states are thus set up. The Hydatid disease in man is caused 

 by the larvae, or echinococci (as they are here called) , from one species of dog's 

 tape-worm, not however the one exhibited. Measles in pork, staggers in sheep, 

 are caused by other varieties. When flesh thus infected is eaten, or the larvae 

 in any way gets into an intestine whose fluids agree with it, the head becomes 

 attached to the mucous membrane by its hooklets, and from its posterior part 

 true tape-worm segments are formed. These multiply very rapidly, and in a 

 short time a perfect tape-worm is produced. 



Under the second microscope, with a four-tenths objective, are some echino- 

 cocci, removed during life from an hydatid cyst, in the liver of a young woman 

 who was successfully operated upon a short time ago at Guy's Hospital by our 

 President. 



These animals are, certainly, not very agreeable ones to have to entertain as 

 guests ; but, apart from their associations, are very interesting to examine and 

 study, from the peculiar changes they undergo. 



The following papers were announced for the next meeting : " On some rare 

 and undescribed Species of Infusoria," by Mr. Tatem, and " On a new Objec- 

 tive," by Mr. M. C. Cooke. 



After the usual conversazione, the meeting terminated. . 



