Like humans, dogs have two sets of teeth in their lives. The 28 baby teeth erupt through the gums between the third and sixth weeks of age. Puppies do not have to grind much food, so they do not have molars. Puppy teeth begin to shed and be replaced by permanent adult teeth at about four months of age.
Deciduous trees shed their leaves usually as an adaptation to a cold or dry season. Most tropical rainforest plants are evergreens, replacing their leaves gradually throughout the year as the leaves age and fall, whereas species growing in seasonally arid climates may be either evergreen or deciduous.
Pig bladders were used in the 19th century to store an artist’s paint. The bladder would be sealed with a string and then pricked to get the paint out. This option wasn’t the best because it would often break open. American painter John G. Rand was the innovator who made paint tubes from tin and screw cap in the 19th century.