EXPERIMENTAL METAPLASIA 355 



readily with methylene blue. The cytoplasm is finely granular, 

 and stains with eosin, but there are no large eosinophil granules. 

 According to Cuenot,('91) thev originate in a 'glande lymphatique' 

 situated at the base of the gills. 



In a former paper (Drew, '10) I have shown in the case of 

 Cardium norvegicum, that when the corpuscles come in contact 

 wilth a rough foreign body, or with injured tissue, they possess 

 the power of agglutinating and forming a compact plasmodial 

 ^mass. In this way bleeding from a small wound is stopped. 

 When the edges of a wound are covered with this mass of agglut- 

 inated corpuscles, proptoplasmic strands are formed across the 

 wound, cotinecting the plasmodia, these strands thicken and con- 

 tract, and so approximate the edges of the wound. 1 have repeated 

 these observatioQs on Pecten, and find that the same phenomena 

 occur, and that a similar plasmodial mass of agglutinated corpus- 

 cles is rapidly formed around any tissue implanted into the adduc- 

 tor muscle. 



That Lamellibranch blood corpuscles are capable of a phago- 

 cytic action towards degenerated cells has been shown by De 

 Bruyne ('96) in the case of Mytilus edulis, Ostrea edulis, Unio pic- 

 torum and Anodonta cygnea. Sir Ray Lankester ('86 and '93) 

 has shown that certain corpuscles of Ostrea edulis have a phago- 

 cytic action on diatoms and minute green algae, and I have 

 shown (Drew, '10) that the corpuscles of Cardium norvegicum 

 have a phagocytic action on bacteria, and are attracted towards 

 extracts of dead tissues. It has also been shown that the cor- 

 puscles of Pecten maximus exercise a similar phagocytic action 

 on dead cells (Drew and De Morgan '10). 



The formation of fibrous tissue around a foreign body implanted 

 into the adductor muscle has been described in a former paper 

 (Drew and De Morgan '10) . The normal fibroblast is an elongated 

 cell, with a spindle shaped nucleus and an indefinite amount of 

 cytoplasm which appears to be drawn out and connected with the 

 neighboring cells by fine fibrillar processes. These cells are usu- 

 ally connected with each other by slender strands of some col- 

 laginous substance, which forms the groundwork of the fibrous 

 tissue, and in the normal resting stage it is often impossible to dis- 



