226 BOTANICAL GAZETTE [OCTOBER 
Payson” has published a monograph of the genus Lesquerella, recognizing 
nd s 
examined are recorded in detail. Preceding the taxonomic presentation, there 
is an interesting discussion of the general morphology, phylogeny, and. geo- 
graphical distribution of the genus 
PETCH,” in continuation of his studies of entomogenous fungi, has pre- 
sented a very detailed account of Hypocrella and Aschersonia. In H ypocrella 
t 
thirteen species are described, four of which are new. In addition to the 
species included in the systematic presentation, a number of species are named 
as not seen, doubtful, or excluded.—J. M.-C. 
rigin of variations.—Of extreme interest to students of genetics is a 
recent number of the American Naturalist which contains the papers presented 
at the Toronto meetings in a symposium on “The origin of variations.” JEN- 
NINGS,”" discussing ° ‘variation in uniparental reproduction, ”’ stresses the fact 
itiv 
induced by environmental changes, which have always reverted to the normal 
type after a certain number of asexual generations. JENNINGS points out that 
the period of persistence of such variations evidently depends, in good part, on 
the number of generations through which the producing agent acted, and . 
expresses the belief that heritable characters, as permanent as any that are 
known to exist, might be produced by allowing the producing agent to act over 
a sufficient period of time. 
BLAKESLEE” describes his work on Datura, which by this time has become 
well known, showing how striking heritable variations accompany changes in 
chromosome number. These changes in ch ber may result either 
aia go ioaianiner of one or a few chromosome sets, producing “unbalanced 
’ or may involve a wholesale doubling of all the chromosome sets, giving 
#9 Payson, E. if hey monograph of the genus Lesquerella. Ann. Mo. Bot. Gard. 8: 
103-236. figs. 34. 
2 PretcH, T., pris in entomogenous fungi. II. The genera — and 
Aschersonia, Ann, Roy. Bot. Gard. Peradeniya 7:167—278. pls. 2-5 
31 JENNINGS, H. S., Variations in uniparental reproduction. i Nat. 56: 
§-I5. 1922 
LEE, A. F., Variations in Datura due to changes in chromosome number. 
Amer. Nat. 56: 16-31. 1922. 
3 Bot. Gaz. 72:178-182. 1921: 
