Answer;
Mesoderm
The mesoderm is a layer of the embryo, which will become the circulatory system, bones, muscles, excretory system, and reproductive system.
Explanation;
-The germ layers develop early in embryonic life, through the process of gastrulation. An inner layer, called endoderm, and an outer layer, called ectoderm and a middle layer called mesoderm.
-The embryonic endoderm develops into the interior linings of two tubes in the body, the digestive and respiratory tube. the lining of the follicles of the thyroid gland and the epithelial component of the thymus.
-Ectoderm develops into parts of the skin, the brain and the nervous system. Mesoderm gives rise to bones, muscles, the heart and circulatory system, and internal sex organs.
Bones are made up of Calcium Phosphate given by the chemical formula, 
. When bones are kept in Hydrochloric acid, given by the chemical formula, HCl, they become soft because the calcium compound present in the bones changes its form. The following double displacement reaction takes place when the bones are kept in HCl,
---> 
Calcium chloride is water soluble, and gets washed away. This makes the bone thin and soft.
HMS Beagle is the name of the ship
No se we pero te dejo un momazo aquí
