488 ENTOZOA. 



In the spring of 1765 I opened the guts of a dog downwards, from 

 the duodenum ; and ahout half-way down I found a great many be- 

 ginnings or heads of tape-worms, all fixed to the inside of the guts. 

 I slit no further, to let the worms die in the guts, to see if they woidd 

 keep fixed after death. Next day I slit open the whole intestine, hut 

 found that, in almost the whole of the worms, the links were separated 

 at their unions to one another ; and that these single links or worms 

 had formed themselves into round ones, as in the former case. When 

 I observed this change they had been in water for some hours ; but by 

 letting them stay in the same water for about twenty-four hours longer, 

 they had altered their shape, and were all become square and thick. 



In a tape-worm taken out of a codfish 1 ) I pressed it flatways, to see 

 if I could squeeze the mucus by natural passages out at the edges ; but 

 I could not do so without a visible rupture. I then squeezed it upon 

 the edges, and found that I easily squeezed out the fluid on one of the 

 sides, and not of the other. On squeezing in this way I found that the 

 side where the mucus easily squeezed out became always round, and the 

 opposite side concave. "Whether it was owing to this circumstance that 

 the mucus squeezed out more easily on the convex side than on the 

 concave, I cannot tell, but it is probable. However, why the same side 

 of the worms should always become convex through the whole length 

 of the worm, I do not know 2 . 



Hydatids 3 . 



The hydatids of the second kind differ very much from the former: 

 they appear to be principally new- formed parts. However, they may 

 be said to be made up of two parts ; one, a thickening of the parts in 

 which they are placed, the other, an adventitious substance formed on 

 the inside of this. 



"When the disposition takes place to form such bodies, it is only in a 

 very small part : but whether the external coat is the first that forms, 

 or whether it is only a consequence of the others, is not easily deter- 

 mined. From some circumstances it would appear to be the latter ; 

 because, when these internal ones have burst from their covering, and 

 become loose in some cavity, they have produced such a stimulus as to 

 have acquired for themselves a vascular coat, similar to that from which 



1 [Probably Bothriocepkahts rugosus, Pud.] 



2 ["This was tbe side on which tbe mouths are placed. — W. C." They are the 

 orifices of the genital organs, and show the tape-worm experimented on to have been 

 a Bothrioccjihalu*.^ 



3 ["Part of this subject had been torn out, having probably been fairly copied; for 

 that which remained had been scored across. — W. C."] 



