RESEARCHES IN HELMINTHOLOGY AND PARASITOLOGY. 9 



in P. lactea,"-^ and when not in use are closely packed together within 

 the animal, so that when the latter is placed beneath the microscope 

 and slightly compressed, they will be seen pressing upon one another 

 in such a manner that if one changes its position it will be instantly 

 occupied by another. Those which are formed last are smallest, but 

 they soon gain their full size. 



When the animal feeds, the whole of them are protruded from the 

 oral orifice, the longest extending out full one-third the length of the 

 body. As they are all convergent to the same orifice, when fully 

 protruded the animal becomes puckered up and increased in breadth 

 at the expense of the length. In this state the anterior extremity 

 is erected and the posterior brought nearly to a right angle with it, 

 so that it looks as if sitting upon its prey apparently unconcerned, 

 with its proboscides, which writhe and twist about as if they were 

 totalh- distinct organisms. 



If one of these animals be punctured or cut, one or more of the 

 proboscides will be immediateh^ protruded as if they existed under 

 pressure, and will move about in all directions, appearing as if en- 

 tirely without the control of the animal ; or if one of the animals be 

 crushed between two slips of glass, so that the proboscides will be 

 torn from their attachment, the}^ move about involuntarih-, always 

 in a line forwards or towards the mouth, which they do by contract- 

 ing the stomachal extremity towards the oral, the latter remaining 

 fixed. In this progressive course they constantly contract and di- 

 late ; the mouth opens and any matter in its vicinitj^ rushes in, when 

 it is closed and the matter pas.ses onwards, and by the alternate con- 

 traction and dilation of different parts of the same tube, it is thrown 

 backwards and forwards several times and finally violently expelled 

 at the torn extremity. When they have escaped from the ruptures 

 of the tegument produced by crushing, or when snipped off with a 

 pair of scissors whilst an animal is feeding, they will present the 

 same curious phenomena. In fact these curious independent move- 

 ments caused me at first to mistake the organ for viviparous young, 

 and it was not until I had frequently observed the animal feeding, 

 and examined its structure beneath the microscope, after having fed 

 them upon coloured food, that I was convinced of their true nature. 



Excrementitious matter is expelled from the digestive cavity 

 through the same course by which the food enters. 



Ciradation. — There appears to be nothing peculiar about the 

 arrangement of the blood vessels, if such they be : the term being 



* Ibid. 



