610 G. II. DUKW AND W. UK MORGAN. 



DESClUPTiON OF J'LATE 24, 



inustratiiig tlio ])a])ci- by Messrs. (i. JJ. Drew and W. de 

 Morgan on " The Origin and Formation <.f Fibrous 

 Tissue produced us a lieaction to Injury in Pecten 

 maxim us, as a type of the Lamellibrancliiatu." 



Rkfekknce Letteks. 

 ncj. Agar. t((jff.lyr. Ag-liiliiiiitcd layer of 1. loud-corpuscles. h.c. 

 Bl..o(l-cori)uscle.s". dcy.ffill. Dcgciieralea oiU-tissue. ch,/. m><l. Degene- 

 va led muscle. di,j.ijl. Digestive gland-tissue, div.fbl. Dividing fibro- 

 blasts, //y/. ?;/>•. Fibroblast layer. mi<j. fhl. Migrating fibroblasts. 

 msl. -fhr. Muscle-fibres. 



[N.B.— In the figures the bundles of nuiscle-fibres are shown as a 

 whole: the individual fibrils and their striations are not dilt'ereiitiated. 

 Tlie size of the uiuscle-buud](>s differs considerably in different parts of 

 the adductor muscle, j 



Fig. 1.— X too. Gill-tissue which has been implanted for sixteen 

 hours. A layer of agglutinated corpuscles divides the degenerated gill- 

 tissue on the left from the niusciUar tissue on the right. Corpuscles 

 are making their way l)etweeu the muscle-filn-es to join the agglutinated 

 layer. 



Fig. 2.— X 30(». A later stage of fig. 1. taken seventy-two hours after 

 implantation. A definite layer of fibrous tissue has been formed round 

 the gill-tissue, which is completely degenerated and invaded by phago- 

 cytes. The fibroblasts are dividing and migrating towards the lesion. 



Pi,r. :5.— X 700. A more highly magnified portion of one of the 

 blood-spaces drawn from the same section as fig. 2. The fil.roblasts 

 are undergoing amitotic division, and migrating towards the gill-tissue, 

 where they arrange themselves to form a layer of fibrous tissue. 



Fig. 4.— X 450. Digestive gland-cells (on the left) which have been 

 implanted for ninety-six hours. External to them is a region of 

 degenerated and partially dissolved muscle-fil'res. which is divided from 

 the normal muscle by a thin layer of agglutinated corpuscles. These 

 are also rapidly degenerating, but are reinforced l)y the continued 

 arrival of fresh corpuscles. The cellular structure of the alveoli of the 

 di«'-estive eland has been lost, leaving little beyond traces of the original 

 cell walls and the brown pigment-granules. 



yi„. .5.— X 450. Agar jelly (to the left) which has been implanted 

 for seventeen days. It is divided from the muscle-tissue by a deUcate 

 layer of fibroblasts. 



