30 The Ottawa Naturalist. [May- 



are also carried by animals. These when wetted become sticky. 

 The moisture causes a coat of mucilage to form all round them, 

 so that they stick to any thing that touches them, and as they 

 dry they become securely gummed to the object, and may then 

 be carried for many days before becoming dislodged. An example 

 of this class will be found in pepper-grass and shepherd's purse, 

 as well as in several others of the cress family. 



V. Seeds that are Spread by Propulsion and Seeds that 

 ARE Spread by Trailing and Climbing Plants. 



In this class are to be found some rather complicated 

 methods of seed distribution. In the case of the violets, the pod 

 bursts open when the seeds are ripe like a great many other 

 seed pods, but in this case the seeds remain in the separate valves 

 or partitions until they are expelled slowly by the drying and 

 contracting of the sides of the valve, which forces the seeds out 

 by squeezing so that in some cases they are thrown several feet 

 away. Anyone who has collected pansy seeds should have 

 noticed this. 



An interesting example of a plant throwing its seeds, as if 

 from a sling, is shown by the common cranesbill, though the 

 method here employed is quite different from the last. 



Another interesting plant is the jewel-weed, or touch-me- 

 not (Impatiens). To thoroughly appreciate the methods em- 

 ployed by this plant in scattering its seeds, I would suggest the 

 readers trying to collect some seeds. When, if a beginner, I am 

 sure he or she will be surprised at the rapidity with which the 

 seeds vanish at the slightest touch, just as if they knew one was 

 after them. 



The peas and beans are also examples of this class of plants, 

 Which by the rapid curling up of the sides of the pod when dry, 

 part of the seeds are thrown some distance away. Many other 

 examples of plants which have special ways of propelling their 

 seeds will be found in any district if looked for. 



The peas and beans also come under the class of plants that 

 spread their seeds by trailing and climbing. Perhaps the best 

 examples of these are members of the gourd family, melons, 

 cucumbers, etc., the seeds of which under natural conditions, by 

 being left where the fruit ripens, would be spread over an area of 

 several feet. Convolvuluses and other climbing plants will also 

 drop their seeds in many cases some distance from the parent 

 plant, but as these plants prefer"some sort of brush to climb up, 



