398 ANNALS XinV YOh'K ACAnnMY OF SCIKSCES 



Summary of Papers 



Dr. Arctowski ^axo llic rcsiill iA his invest iniitiiiiis mi the iiilhicnce 

 that the violent eruptions oJ' the years 1883, 1902 and 1912 have had 

 upon atmosplicric temperature. 



It was found that the pleionian vMriatiops of tempcratui-c changes have 

 nothing in common ^itli the presence or ab'sence of volcanic dust veils; 

 that the dust veils produced by the Krakatoa eruption affected atmos- 

 pheric temperature very greatly and that the violent volcanic eru])tions 

 of 1902 as well as the Katniai eruption of 1912 influenced the yearly 

 mean temperatures but very slightly or not at all. 



This paper was discussed by Professor Kemp and others. 



Mr. Mock said: A study was made upon ii\(' mutations of Spirifer 

 mucronatvs from the Hamilton beds of Michigan and Ontario. Many 

 specimens were measured, and shell indices were computed by dividing 

 the width of the shell by its length. Curves were plotted of the per- 

 centage of the total number of indivitluals measured of each mutation, 

 with indices between certain arbitrary limits, both for adult and neanic 

 stages. Comparison was made between the curves of the adult and neanic 

 stages of each mutation, and of the curves of tlie adults of the various 

 mutations with each other. 



The tendency in evolution has been to reduce the shell index, reduce 

 the number of plications, lose the groove on the fold and the plication 

 in the sinus, strengthen the growth lines, deepen the sinus, and to a 

 certain extent to reduce the actual width of the shell. 



The paper was discussed by Mr. F. T\. Morris and Prof. A. W. Oi-aban. 



The Section then adjourned. 



A. B. Pacini. 



Secretanj. 



SECTION OF BIOLOGY 



14 Deckmber, 1914 



Section met at 8:15 v. m.. Professor Raymond C. Osburn presiding. 

 The minutes of the last meeting of the Section were read and ai)proved. 

 The following programme was then offered : 



Sympos]u:m on Porto Pico 



Charles P. Berkey, (;i:oi,()<;i( ai, Pecoxxaiss.ance or Pokto 



Rico. 

 N. L. Britten, Progress of the Botanical Investigation. 



