A STUDY OF RESTITUTION MASSES. 



451 



turbed, there seems to be no tendency for these nodules to change their 

 position, but if they are disturbed by shaking or rotating the watch- 

 glass so that they are brought into contact with one another they mutually 

 adhere, and in the course of some hours may give rise to one or more large 

 restitution masses in which no trace of the smaller nodules originally 

 formed can be distinguished. 



Similarly if the watch-glass, immediately after the cells have been 

 squeezed into it, be rotated so that all the cells form a compact heap in 

 the centre, the restitution masses may be formed as one or more thick 

 flat cakes with rounded edges without the preliminary formation of the 

 smaller nodules described above. 



THE MORPHOLOGY AND DURATION OF LIFE OF 

 THE RESTITUTION MASSES. 



The after history of a restitution mass depends very much on its 

 original size when first formed, and this again depends on whether the 

 dissociated cells were shaken together or allowed to form the small 

 nodular masses already described. 



When one of these larger masses of tissue is first formed it consists 



Fig. 5. *k 16. — A restitution mass 8 days old, show- Fig. 6. X 16. — A restitution 

 ing curling up and nodulation of edges. mass 34 days old, showing 



well-marked shrinkage away 

 from the perisarc and fe- 

 nestrated appearance of the 

 cell mass. 



of a flat cake of tissue of irregular shape, sometimes adherent to the 

 glass. During the first 12 hours after its formation, a considerable amount 

 of alteration in shape occurs, the edges of the mass turn up away from the 

 glass, and a good deal of retraction takes place and consequently the 

 tissue becomes stronger and more compact. After from 12 to 18 hours 

 a delicate, transparent, colourless membrane is secreted round the mass, 

 completely enclosing it and forming a tough protecting layer : this layer 



