14 Proceedings of the 



Tlie report was accepted, and on motion a warrant was or- 

 dered drawn on the Treasurer for the amount of $9.05. 



On motion a warrant Avas ordered drawn on the Treasurer 

 for $2.50 for the bill of Fiske & Douglas. 



It was then moved and supported that hereafter and until 

 further notice, the time of meeting of the Association be changed 

 to 8 P. M. Carried. 



Prof. Harrington, in behalf of Bryant Walker and Charles 

 E. Beecher, presented a paper comprising a list of the land and 

 fresh-water shells found within a circuit of four miles about Ann 

 Arbor, and collected by them. (See Appendix B. ) 



On motion, Messrs. Walker and Beecher were made a com- 

 mittee to make any additions and changes in the list which future 

 observations should make necessary. 



On motion. Miss Mary H. Clark and Miss E. C. Allmen- 

 dinger were made a committee to make out a list of plants found 

 growing within a radius of four miles of Ann Arbor. 



Mr. R. W. Corwin was appointed a committee to make a list 

 of all vertebrates, except fishes, found within the same radius. 



Dr. W. H. Jackson was now introduced, and read a very 

 interesting paper on "Hypertrophic Cement," illustrated by 

 microscopic specimens and diagrams. He spoke first of the 

 causes of hypertrophy in general, and then of hypertrophic ce- 

 ment under two heads : 



First. The primary causes, — such as inflammation of the 

 periosteum, death of the pulp, abnormal secretions of the mouth 

 producing irritation of the gums or of the sentient terminal 

 nerves in the dentine, irritation of the periosteum-dentine from 

 undue i)ressure. 



Second. He spoke of its histological structure and form 

 as cap-shaped, laminated, modulated and penetrating. 



There is no time of life between the formation of the tem- 

 porary teeth and that of old age that is exempt from this hyper- 



