February 13, 1903.] 



SCIENCE. 



261 



Studies in Aracea: Douglass H. Camp- 

 bell, Stanford University. 

 The material was collected at Kew. The 

 species especially studied were Aglaonema 

 commutatum and' Spathicarpa sagittcefolia. 

 Aglaonema commutatum shows extraor- 

 dinary variation in the development of the 

 embryo-sac. The ordinary angiospermous 

 type was never found. The number of 

 nuclei in the mature sac is probably, in 

 most cases, eight, but may be as many as 

 twelve. A definite egg apparatus and 

 antipodal cells are rarely met with, and 

 the former is rarely at the micropylar end 

 of the sac, but usually lateral in position. 

 Three or four nuclei are often found in 

 process of fusion, presumably as a prelim- 

 inary to the endosperm formation. The 

 formation of the endosperm proceeds from 

 the base of the sac; cell walls are present 

 from the first. The tissues of the young 

 embryo are very little differentiated; at 

 maturity it fills the embryo-sac. A. pic- 

 tum conforms to the ordinary angiosper- 

 mous type. 



Spathicarpa sagittcefolia shows no 

 marked deviation from the angiospermous 

 type except in the great development of 

 the antipodal ceUs subsequent to fertiliza- 

 tion. The nuclei of the antipodal cells 

 attain enormous dimensions. The devel- 

 opment of the endosperm is much as in 

 Aglaonema. The embryo is small. 



A Preliminary Synopsis of the North 

 American Species of the Genus Mitrula: 

 E. J. DuRAJTD, Ithaca, N. Y. 

 During the last summer species of the 

 genus Mitrula were unusually abundant 

 in the vicinity of Ithaca, N. Y. Photo- 

 graphs and full descriptive notes were 

 obtained of so many species (some of which 

 were undescribed) that it seemed desirable 

 to attempt an arrangement of the North 

 American species. A general preliminary 

 synopsis of these species makes up the bulk 



of the paper. Fui'ther study of material 

 in the large herbaria will be necessary be- 

 fore the paper will be ready for publica- 

 tion. 



On a Fungus Disease of the Mulberry 

 Fruit: W. A. Orton, Department of 

 Agriculture, "Washington, D. C. 

 This paper gives a brief description of 

 a disease of the mulberry in the southern 

 states caused by an undescribed fungus 

 which fills the seed. Specimens of the 

 infected seeds, and also slides and draw- 

 ings, were exhibited. 



Numerical Variation in Plants: Jesse B. 



Norton, U. S. Department of Agricul- 

 ture, Washington, D. C. 



A review of past work in this line — 

 Ludwig's work and his approach to a log- 

 ical explanation of the Tibonacci series of 

 3, 5, 8, 13, etc., as based on phyUotaxy — 

 other literatm'e— place and time, modes, 

 etc. 



The importance of phyllotaxy and antho- 

 taxy in considering numerical variations, 

 illustrated with curves constructed on the 

 variations in numerous plants— Sangui- 

 naria, Chrysanthemum leucanthemum, 

 Eanunculus, etc. 



The lack of regularity in phyllotaxy 

 and variation of anthotaxy in individual 

 plants and flowers as a cause of secondary 

 modes in variation curves, illustrated by 

 Chrysanthemum leucanthemum, also the 

 relation of the whorled series 1, 2, 4, 8, 16, 

 3, 6, 9, 12, etc., to the alternate series 

 1, 3, 5, 8, 13, etc., and its multiples, as giv- 

 ing modes in different species not in per- 

 fect accord with the Fibonacci series. 



The relation of double curves and in- 

 dividual plants showing tendency toward 

 single curves in individual plants — Chrys- 

 anthemum leucanthemum — and changes in 

 anthotaxy in individual heads. 



The relation of reversed and normal 

 phyllotaxy and anthotaxy to the change 



