FIBROUS TISSUE PKODUCED AS A REACTION TO INJURY. 609 



there is a progressive extensiou of tliis digestive tictiou shows 

 that the hiyer of agglutinated corpuscles performs its pi'O- 

 tective function very completely^ as otherwise the enzymes 

 would escape into the general circulation. Simultaneously 

 the fibroblasts in the vicinity multiply and migrate, as in the 

 case of implanted gill-tissue, but the multiplication does not 

 seem to be so rapid. No permanent layer of fibrous tissue is 

 formed, as the migrated fibroblasts are dissolved in the course 

 of the extension of the sphere of action of the digestive 

 ferments. 



In the case of the implantation of sterile agar jelly, made 

 with sea-water, no inflammation results, and for some time 

 there is no sign of any reaction of: the tissues if absolute 

 asepsis has been ensured. After seven or eight days there 

 is a slow and often mitotic division of the neighbouring fibro- 

 blasts ; they migrate and rearrange themselves to form a 

 thin layer of fibrous tissue around the agar. 



It is noteworthy that though the tissues and the blood, 

 especially in its manner of forming a " clot," present marked 

 differences from those in Vertebrates, yet the formation of 

 fibrous tissue^ as a reaction to injury, does not differ in any 

 essentials from the process which takes place in the higher 

 types. 



References. 



1. Cncnot. L. — " litiules snr le Sang et les Glandes Lymphatiques," 



' Arcli. de Zool. Expor. et Gen.,' Deuxieme serie, tome ix, Paris, 

 1891. 



2. Dakiii, W. J. — "Pecten." 'Liverpool Marine Biological Committee 



Memoirs," xvii, London, 1909. 



3. De Bruyne. C. — " Contribution a I'otude de la Pliagocytose (1),"' 



• Arcli. de Biol.." tome xiv, Paris, 1896, p. 161. 



4. Drew, G. H. — " Some Points in the Physiology o£ Lamellibranch 



Blood-Corpnscles," ' Quart. Journ. Micr. Sci.,' vol. 5-1, part 4, 

 February, 1910, p. 605. 



5. Lankester. Sir E. Ray. — " On Green Oysters," ' Quart. Journ. Micr. 



Sci.,' vol. 26, 1886, p. 71. 



6. " Phagocytes of Green Oysters," ' Nature,' vol. xlviii, 1893, 



p. 75. 



VOL. 55, PART 3. NEW SERIES. 40 



