AN OUTLINE OP PHYTOBIOLOGY. 23 



stony as in the grape, or by inner part of the ovary ripening to 

 a stone as it does in the peach and cherry. In many cases the 

 seeds are enclosed in a core which is not eaten but thrown away 

 after being carried some distance. Seeds escape being crushed 

 by the teeth either by their minute size, or by being large and 

 bitter, or by being very slippery, or by being too hard. 



The pulp may be formed from bracts as in juniper, from the 

 receptacle as in the strawberry, from the calyx as in wintergreen, 

 from wall of the ovary as in the grape, from placentas as in 

 watermelon, from the arillus as in mace, yew, from the funi- 

 culus as in some cactuses, from hairs on the interior wall of 

 the ovary as in aroids and the orange, or the pulp may be formed 

 from several of these combined. 



6. In some plants, seeds or fruits, more or less protected l)y 

 hard coats against danger of digestion, look so remarkably like 

 insects that it is believed by some botanists that their resemblance 

 is not accidental but the result of adaptation, and that they ai-e 

 swallowed by animals in the belief that they are insects, and are 

 later discharged uninjured. Such are the seeds of the castor 

 bean and of Jatrophn, which i-esemble beetles, and fruits of 

 Scorpiurus and Calendula which resemble caterpillars. But the 

 subject is not yet settled. In other cases very brightly colored 

 seeds may be swallowed precisely as other brightly colored 

 objects, such as bright pebbles, etc., are. Certain seeds, Melam- 

 pyrum pratense^ resemble very closely the eggs of ants and are 

 probably carried off in that belief. 



7. Man has produced great effects upon plant locomotion. 

 He has carried useful plants from one continent to another and 

 through all lesser distances : along with the seeds of these, he 

 has accidently introduced others, which may run wild and become 

 weeds, and finally in various accidental ways he has scattered 

 them around the glolie. All of this locomotion is, however, of 

 the incidental, not of the adapted kind. 



