182 The Healing of Incisions in Vegetable Tissues. [Dec. 12, 



but represent a true structural peculiarity of this tissue. That these 

 varicosities, which often continue in an uninterrupted Hue across 

 large fields of view, correspond with the course of one set of fibres. 

 The varicosities may, therefore, be caused by the presence of this set 

 of cross fibres. The only alternative explanation which has occurred 

 to me is that there may be a rhythmic, simultaneous action of all the 

 ameloblasts concerned in the deposit of the material for enamel 

 building. The last theory seems to be less reasonable than the 

 first.* 



7th. The Retzius bands are often as distinctly marked in forming 

 as in mature teeth, and in teeth which have been kept constantly 

 moist as they are in dried specimens. The enamel rods are often 

 seen to pass without break across several of these bands. The bands 

 are principally due to a deposit of pigment, and not to imprisoned 

 air or gas as claimed by von Ebner. 



V. " The Healing of Incisions in Vegetable Tissues." By 

 Samuel G. Shattock. Communicated by Sir James 

 Paget, Bart., F.R.S. Received December 4, 1895. 



(Abstract.) 



The five methods of wound repair in man and the higher 



animals : — 



(1) Immediate union. (2) Primary adhesion. (3) Granulation. 

 (4) Secondary adhesion. (5) Beneath a scab. 



The third and fifth concern the healing of open wounds, and are 

 referred to only incidentally. 



Immediate Union, i.e., union of the cells actually divided. — Never 

 observed. Experiments made on the planule of Faba vulgaris. 



Primary Adhesion. — All growing parenchyma readily heals after 

 incision. Mode of experiment. 



(a) Healing by primary adhesion without separation of surfaces. 



(1) Without sclerosis of the scar-tissue. In the shoots of Aucuba. 

 Stages : Cell division on either side of the incision ; absence 

 of suberisation ; interruption of the line of the adpressed re- 

 mains of the opened cells by the interpolation of new. The 

 absence of cork formation not due to inability to form it. 



(2) With sclerosis of the scar-tissue. In kohl-rabi. The line of 

 scar- tissue broken by the growth of indifferent parenchyma. 



* Since the above was written, I have demonstrated that there is a simultaneous 

 deposit of the spherical bodies over the entire surface of forming enamel. — J. L. W. 



