May 11, 1900.] 



SCIENCE. 



751 



here obtained was thirty feet long. The granite 

 veins have also been described by Van Hise. 



Discussion followed on occurrences of extra- 

 ordinarily large crystals of other minerals. 

 Theodore G. White, 

 Secretary of Section. 



THE ACADEMY OF SCIENCE OF ST. LOUIS. 



At the meeting of the Academy of Science 

 of St. Louis, on the evening of April 16th, Mr. 

 Herbert F. Roberts, of the Henry Shaw School 

 of Botany, addressed the Academy on ' The 

 Structure and Physiology of the Cell in the 

 Plant Organism.' The history and develop- 

 ment of cytology as a special field in biology 

 were traced, and the origin of the various 

 theories of cell organization was indicated. The 

 development of various theories respecting the 

 ceutrosome and its r61e in cell division was 

 discussed, the homologues of the centrosome 

 to be found in ciliated cells and spermatozoa 

 being indicated. After a review of the proc- 

 esses of cell division and their attendant phe- 

 nomena, the methods of study of mitoses in 

 plants and their proper illustration were con- 

 sidered. A great need exists for more accurate 

 processes of reproduction than is afforded by 

 plates made from camera lucida drawings. The 

 latter are always more or less diagrammatic, 

 and are apt to be modified by the personal bias 

 of the investigator. Unconsciously the per- 

 sonal equation enters in. This is seen in recent 

 work on the subject of the existence of the cen- 

 trosome in higher plants. The difficulty referred 

 to can be overcome by the employment of pho- 

 tomicrography. This has been made use of to 

 a limited extent by zoologists in the study of mi- 

 toses, but apparently scarcely at all by botanists. 

 The speaker showed some forty prints from 

 photomicrographic negatives showing mitoses in 

 rhizomes of Erythronium albidum and in micro- 

 spore mother cells, and microspores in Lilium 

 philadelphicum and Pinus laricio and megaspores 

 in Lilium Canadense. The possibility which pho- 

 tomicrography affords, of giving structural de- 

 tails with relative fidelity, was illustrated by 

 these photographs and by lantern slides. 



Eight persons were elected active members 

 of the Academy. William Tbelease, 



Recording Secretary. 



AMERICAN mathematical SOCIETY. 



A REGULAR meeting of the Society was held 

 at Columbia University on Saturday, April 28, 

 1900. As has grown to be the custom, a por- 

 tion of the day was set apart for a joint meet- 

 ing with the American Physical Society, at 

 which papers noted below were read by Profes- 

 sors E. W. Brown and R. S. Woodward. Presi- 

 dent Woodward occupied the chair, yielding it 

 during the joint session to Professor Hallock, of 

 the Physical Society. The amendments to the 

 constitution outlined in the report of the Feb- 

 ruary meeting were adopted. The following 

 persons were admitted to membership : Profes- 

 sor R. D. Ford, St. Lawrence University, Can- 

 ton, N. Y. ; Dr. L. W. Reid, Princeton Univer- 

 sity, Princeton, N. J. Eight applications for 

 membership were received. 



The following papers were presented at this 

 meeting : 



(1) De. Virgil Snyder: 'On some invariant 

 scrolls in coUineations which leave a group of five 

 points invariant. ' 



(2) Mr. a. S. Gale : ' Note on four theorems of 

 Chasles. ' 



(3) Professor Charlotte Angas Scott: 'A 

 theorem on quadrilaterals in space.' 



(4) Mr. p. H. Loud : 'Sundry theorems concern- 

 ing n lines in a plane.' 



(5) Dr. E. J. WiLCZYNSKi : 'Transformation of 

 systems of linear differential equations. ' 



(6) Professor Florian Cajori : 'Semi-conver- 

 gent and divergent series whose product is absolutely 

 convergent.' 



(7) Professor E. W. Brown: 'A possible ex- 

 planation of the eleven year period of sunspot activity.' 



(8) Professor R. S. Woodward: 'An elemen- 

 tary method of integrating certain linear differential 

 equations. ' 



(9) Dr. G. a. Miller: 'On a certain class of 

 ahelian groups. ' 



(10) Professor H. E. Newson : 'On singular 

 transformation and continuous groups.' 



(11) Professor E. O. Lovett: ' Group theory and 

 geometry of four dimensions. ' 



(12) Professor E. O. Loveti: 'The condition 

 that a linear total differential equation be integrable. ' 



(13) Professor C. H. Hinton : 'Observations on 

 the principle of duality.' 



After the meeting several members of the 

 Mathematical and the Physical Societies dined 

 and passed the evening agreeably together. 



