238 STUDIES IN THE EVOLUTION OF ANIMALS 



the utmost service for purposes of recogjiition and discovery, by 

 leaving traces on the high grass through which they may have 

 passed, or in which they may have hidden themselves. Mr. F. C. 

 Selous mentions that on being attacked by natives one night, he 

 and his men escaped into the jungle grass, which was seven feet 

 high} In the midst of tall grass, neither keen sight nor keen 

 hearing would be of much avail, but by leaving a scent on the 

 grass which rubbed against the leg glands, as the animal passed 

 through, its companions might succeed in rejoining it. When 

 hunted by a carnivorous animal, it would have been an advantage 

 for a herd to scatter, and hide themselves among grass. If they 

 did so, it would have been an advantage to be able to find each 

 other again by leaving scent-traces on the grass. Sir W. Flower 

 says — ' Some Deer and Antelopes have a suborbital gland secreting 

 a peculiar oily odorous substance.' When the animal is feeding 

 drops fall on the herbage and indicate to others the whereabouts 

 of animals of the same species. It is not improbable that the leg 

 glands had some similar use. 



Just imagine how useful such a trace would have been to the 

 dam in finding its young one, and to the young one in finding 

 its dam, when they may have wandered away from each other 

 in the midst of high grass. 



Think how useful they would have been in the rutting season 

 among high grass to the male in finding the female and vice versa. 

 As I said, such glands were very probably of the same nature 

 as those in front of the eye of certain Deer. 



The reader might perhaps ask — How is it that all the rumi- 

 nants have not traces of leg glands? Well, the same question 

 might be put regarding the suborbital gland, for not all Antelopes 

 and Deer have it. We don't know sufficiently the early history 



^ In South America miles and miles of plains are covered with the tall Pampas grass. 



