NATURE NOTES 75 



that the outlines simply suggest questions, experiments and lines of study ; 

 and various reference books are supposed to give the supplementary informa- 

 tion needed. 



Departments of Agriculture Publications. Of interest in connec- 

 tion with nature-study and elementary agriculture are the following recent 

 bulletins - : " Grouse and Wild Turkeys" (Bull. 24, Biol. Survey, 10c. 

 "Horned Larks" (Bull. 23, Biol. Survey, 5c.) ; "Guinea Fowl' 

 ( Farmers' Bull. 234, free) ; " Incubators " (Farmers' Bull. 236, free) ; 

 " Bobwhite and other Quails "( Bull. 21, Biol. Survey, 5c); "School 

 Gardens" (Bull. 60. Exp. Stations, 10c); "Game Laws for 1905' 

 (Farmers' Bull. 230, free); "Maple Sugar Industry " (Bull. 59, Bureau 

 Forestry, 5c); "The Boll Weavil " (Bull. 51, Entomology, 15c); 

 " Annual Loss by Insects" (Ext. 360, 1904 Yearbook, free) ; " Game 

 Protection and the Farmer " (Ext, 364, free). 



NATURE NOTES 



Defenses Of Cock-spur Thorn. In a note in the November issue of 

 this magazine doubt was expressed concerning the view that the thorns are 

 primarilv developed for protection. In the December Plant World Dr. W. 

 N. Clute, editor of The American Botanist, writes as follows : 



" If you will go into the nearest pasture set with hawthorn, you may 

 have abundant evidence to show that cows do not refrain from eating the 

 hawthorns, thorns or no thorns. Quite on the contrary, they apparently 

 consider them good forage, for everv starveling shrub is kept sheared ot its 

 tender twigs throughout the summer. The only way in which the shrub 

 can outwit its enemv is to continue to put out side shoots from year to year, 

 letting the cows nip the young and tender tips but making what is left stout 

 and woody until it has formed a bush so wide that no cow can reach the 

 center from any side. Then the shoots in the center may carry the shrub 

 upward, and this they immediately do. Every thorny pasture is full of these 

 bushv shrublets biding their time. 



After the shrub has got beyond the stage where the cows can no longer 

 keep its leaders down, the cows continue regularly to trim up the side 

 branches. We are, I believe, to look for the cause of thorns in these plants 

 to some inherent quality of the plants themselves. There are certain fami- 

 lies of plants that run to ihorniness and several of these are centered around 

 the rose family. There are many thorny species among the legumes and in 

 the rose family, to which the hawthorn is most closely related, e. g., black- 



