292 



SCIENCE 



[N. S. Vol. XLIII. No. 1104 



15 chromosomes were counted in a form produced 

 by Lamarckiana, bearing a number of characters 

 in common with type 5,509. Fifteen (?) chromo- 

 somes were counted in 0. elliptica (Lamarckiana 

 mutant) — number not determined precisely — and 

 in an unnamed mutant from one of de Vries 's 

 1912 cultures of 0. lata X 0. Lamarckiana, sa^d 

 to combine the characters of 0. lata with the 

 smooth, shiny leaves of 0. laeta. Only 2 of the 

 11 distinct types in which 15 chromosomes were 

 counted precisely by the writer had lata or lata- 

 like characters; namely, 0. lata and 0. nanella 

 lata. Many other named and unnamed mutant ofiE- 

 spring of 0. Lamarckiana and other 14-chromo- 

 some types which can not be designated as lata- 

 like forms, indicate by the nature of their somatic 

 characters or hereditary behavior, or both, that they 

 have 15 chromosomes; for example, 0. seintillans, 

 0. sublinearis, 0. leptocarpa, etc. — mutant off- 

 spring of 0. Lamarckiana; and 0. nanella oblonga, 

 0. nanella elliptica, etc., produced by 0. nanella. 

 While it is possible that 9- and 6-chromosome 

 gametes, capable of functioning, may be produced 

 by 14-ehromosome forms occasionally, that a 9- 

 might unite with a 6-, in rare instances, and pro- 

 duce one of the uncommon types of 15-chromo- 

 some mutants, it is probable that most 15-ehromo- 

 some offspring of 14r-chromosome forms, particu- 

 larly the common types — whether Zato-like or not — 

 result from 8-7 unions. Of particular interest, in 

 connection with this discussion, is the fact that 

 a toia-like mutant appeared in a 1908, and another 

 in a 1910, culture of Lamarckiana pollinated by 

 Lamarckiana. The two did not duplicate each 

 other nor 0. lata, and each had 16 instead of 15 

 chromosomes. They may have arisen from 8-8 or 

 9-7 unions. 



A Comparison of the Wood Structure of CEno- 

 thera stenomeres and Its Tetraploid Mutation 

 gigas: "W. W. Tuppee and H. H. Bartlett. 

 The change from the 2a; to ix chromosome num- 

 ber in 0. stenomeres is concomitant with (1) An 

 increase of 50 per cent, in the length of the ves- 

 sels, and of 150 per cent, in the area of the cross- 

 section. (2) An increase of 50 per cent, in the 

 length and diameter of the tracheids, correspond- 

 ing to an increase in volume of 200 per cent. (3) 

 An increase in all three dimensions of the ray 

 cells, but not a proportional increase, resulting in 

 a cell of a different shape with an increase of 

 275 per cent, in volume. (4) A breaking up of 

 the tall multiple medullary rays into their con- 

 stituent simple rays 



Ortliogenetic Saltation in Nephrolepsis: E. C. 



Benedict. 



The title, " Orthogenetic Saltations in Nephro- 

 lepsis," was selected to emphasize two points: 

 First, the variations to be described are discon- 

 tinuous and of considerable magnitude, i. e., 

 "jumps" or saltations; second, these variations 

 are definitely directed (orthogenetic) along a few 

 distinctly limited lines. The present consideration 

 is purely descriptive. The variations dealt with 

 are all from one variety, iostoniensis, of the spe- 

 cies, N. exaltata. From this variety have come at 

 least three distinct lines of variation, viz., pro- 

 gressive dwarfing, progressive increase in division 

 of leaf, and progressive increase in waviness of 

 leaf. The illustrations to be given are as follows: 



Progressive dwarfing: (1) icstoniensis — Scotti 

 — Wagneri. (2) Boosevelti — Teddy, Jr., — ^new 

 form as yet unnamed. 



Progressive increase in division of leaf: (1) ios- 

 toniensis — Piersoni — Barrowsi — Whitmani — magni- 

 fica. (2) Scotti — Scholseli (2-pinnate) — Scholzeli 

 (3-pinnate). 



Progressive increase in waviness of leaf: (1) ex- 

 altata — bostoniensis — Sarrisi — Wm. K. Harris. 



Another type of variation, not progressive but 

 retrogressive, is shown in the reversion forms 

 which, however, can not be mentioned in detail 

 here. Finally, two points are to be emphasized. 

 There are at least sixty different sports of ios- 

 toniensis, nearly all of which may be placed in one 

 of the series mentioned above. These variations 

 are all vegetatively produced. 

 An Interesting Modification in Xanthium: Ohaeles 



A. Shull. 



A peculiar modification of the burs of Xanthium 

 is described, in which the number of the flowers 

 surrounded by the involucre has been greatly in- 

 creased. In one specimen, a cross section of the 

 bur showed the presence of twenty-six involucral 

 cavities. Twenty-three of the cavities contained 

 the remains of ovarial walls, twelve of which had 

 normally developed seeds, and eleven of which had 

 aborted. Three cavities showed no indications of 

 ovaries, but their position is evidence of their na- 

 ture. The manner in which this form originated 

 is unknown, but it seems probable that it is either 

 a mutation or a reversion from X. canadense. 

 Unfortunately this interesting variety was extinct, 

 so far as the local appearance is concerned, at the 

 time it was received. H. H. Babtlbtt, 



Secretary 

 (To be cont 



