604 a. II. IM.'KW AM) W. !)!■; Moj.MIAK. 



was iiii|)l;uit.(j(l lived lono- ciioii<^li lor ;i,il the elements (A tlie 

 gill-tissue to bo completely replaced by libi-(jus tissue, hiiL in 

 healthy specimens most ol the signs ol inflammation liad 

 vanished, and the implanted tissue was surrounded by a wall 

 of apparently hcjilthy fibrous tissue, in foui- or five dnys. 



Formation of Fibrous Tissuk around 'jiie sitk of implanted 



Digestive Gland Cells. 



After the im})lantation of portions of the digestive gland, 

 ;i, nnirked degeneration of the muscular fibres in its neigh- 

 bourhood is noticeable. They swell slightly, all trace of 

 striation is soon lost, and they stain less intensely. The area 

 of degeneration gradually extends, and the muscular fibres 

 ill the immediate neighbourhood of the gland tissue are slowly 

 dissolved. This action is presumably due to the presence of 

 ferments in the digestive gland, which digest and render 

 soluble all tissues in the immediate neiirhbourliood. At the 

 same time the cells of the gland itself degenerate and appear 

 to undergo auto-digestion, so that eventually only the brown 

 pigment-granules originally contained within the secreting 

 cells remain. Undei- these conditions bacteria do not seem 

 to multiply, though they must have access to the cajca of the 

 digestive gland, as these are in direct communication with 

 the alimentary canal. In none of our sections have we been 

 able to find bacterici, though it is quite common to find the 

 siliceous skeletons of diatoms in the cieca. It seems, there- 

 fore, probable that the presence of digestive ferments inhibits 

 the multiplication of bacteria. 



As a result of the implantation of this tissue a condition 

 of intense inflammation is set up, and all the blood-spaces in 

 the neighbourhood become distended with blood-corpuscles. 

 There appears to be an endeavour on the part of the orga- 

 nism to shut off all the implanted gland, together Avith the 

 area of muscular tissue which has undergone degeneration, 

 from the general blood-stream. This is effected by the 

 formation of a layer of agglutinated blood-corpuscles around 



