344 



THE AMERICAN NATURALIST [\^ol. XLI 



of their development in two species. The modifications are introduced 

 in the nymph stage and are almost complete in the subimago, though 

 the eyes rapidly increase in size at the time of the final molt. Shafer 

 thinks that the two divisions of the eye are for \dsion in different kind 

 of light the regions with larger elements and less dense pigmentation 

 being available in twilight or in the darker hours. 



Notes. — Dr. Lawrence E. Griffin has published in the Missouri 

 Valley College Quarterly Bulletin, (6, No. 4, 1907) a handy guide to 

 the dissection of the dogfish (Acanthias & Galius). Copies may be 

 had from the author at Marshall, Missouri, at 25 cents each. 



BOTANY 



Winter Rest.— In a very comprehensive series of experiments,^ 

 in one of which as many as 283 species were used. Dr. Waher L. 

 Howard, of Columbia, ]\Io., has studied the effect of increase of 

 temperature, narcotics, lack of light, and dehydrating agents upon 

 plants in the resting condition. He comes to the conclusion that 

 the resting period is due to external influences, which also determine 

 its duration and intensity. It may be interrupted by the use of the 

 above mentioned agents. Though the results they produce are identi- 

 cal, their action is different. An am})le citation of literature enhances 

 the value of this paper. 



Henri Hus. 



Notes. — A quarto of 340 pages, devoted to a revision of the genus 

 Lcjjidiuiii ])>• Tliclhmg, has been separately issued from vol. 41 of 

 the Xrw )h>,hsr}rnjtni der AUgem. Schweizerischen Gesellschajt 

 /. (/. (icsnmini Xatiirwlsscnschaften, as a contribution from the Zurich 

 Botanical ^Vluseuu). 



Some of the difficulties of cactus study are ])ointed out by Griffiths 

 and Hare in an economic leaflet issued as Bnllrtin 7W. iO,>, part 1, of 

 tlie Buivnii (.f Plant Industry. 1". S. Dcpiirtincnt of AgricuUure. 



( )l,.(Tv;. liens on SaiTa. rni;i aiv | .ul .lislic( 1 l,y Macfarlane in The 

 Journal oj Hnhinf/ tor .lanuary. 



Pflanzen. Inaugural-dissertation, Halle^ 1906. pp.111. 



