106 DR. REDFERN, ON THE TORBANEHILL 



mass from the body, about one-fourth of the whole. The two 

 portions afterwards retained their form with a puckered mark 

 at the point of separation. The micleus was not involved in 

 this operation, which occupied about two hours. 



It is also a matter of every-day observation, that when the 

 body has been torn and nearly all the contents have been lost, 

 the animal continues to live in a deformed state, if the nucleus 

 and central parts are left together. They acquire a new in- 

 vestment, or a portion of the original integument gathers up 

 round them, while the ragged shreds are cast off. 



When several of these creatures have been kept for some 

 time in still water, it is not unusual to find two of them in 

 apposition ; but 1 have never discovered any indications of 

 conjunction, and look upon the condition as one of mere 

 adhesion. It may, however, have given rise to the mention 

 of double individuals, as the adhesion is tolerably firm. It 

 may easily be broken up without injury to either animal. 



The nucleus may be demonstrated as a nucleated vesicle, 

 sometimes solitary, more frequently with several similar, but 

 smaller nucleated vesicles grouped around it. By careful 

 manipulation it may be removed from the other structures. 

 As it floats about, the true form is displayed. Seen in one 

 position, you have a view of a round vesicle with a smaller 

 vesicle attached to it by a sort of hour-glass contraction ; in 

 another, of a round vesicle with a central spot, a nucleated 

 cell. 



I have found the nucleus enclosed in a second membranous 

 envelope, with a granular yelk-like fluid, which could be seen 

 pouring out when the membrane gave way (fig. 10). 



Beyond this point 1 have not been able to trace the nucleus. 



On the Nature of the Torbanehill and other Varieties of 

 Coal. By Peter Redfern, M.D., Lond., Lecturer on An- 

 atomy and Physiology, and on Histology, in the University 

 of Aberdeen. 



(Read at the Meeting of the British Association for the Advancement 

 of Science at Liverpool, 1854.) 



The substances to which I intend to allude in the following 

 paper, under the name of coal, are such as, Imou-n commonly as 

 coal, consist of compressed and chemically altered vegetable 

 matter, associated loith more or less of earthy substances, and 

 capable of beiny used as fuel. 



Though I shall confine myself chiefly to the structural cha- 

 racters which coals present, I shall refer briefly to their chief 



