Describe the chromosomal theory of inheritance.

(N/A) Mendel published his work on the inheritance of characters in $1865$,but for several reasons,it remained unrecognized until $1900$.
Firstly,communication was not easy in those days,and his work could not be widely publicized. Secondly,his concept of genes (factors) as stable and discrete units that controlled the expression of traits and of the pair of alleles which did not 'blend' with each other was not accepted by his contemporaries as an explanation for the apparently continuous variation seen in nature.
Thirdly,Mendel's approach of using mathematics to explain biological phenomena was totally new and unacceptable to many biologists of his time.
Finally,though Mendel's work suggested that factors (genes) were discrete units,he could not provide any physical proof for the existence of factors or explain what they were made of.
In $1900$,three scientists (de Vries,Correns,and Von Tschermak) independently rediscovered Mendel's results on the inheritance of characters.
By this time,due to advancements in microscopy,scientists were able to carefully observe cell division.
This led to the discovery of structures in the nucleus that appeared to double and divide just before each cell division. These were called chromosomes (colored bodies,as they were visualized by staining).
By $1902$,the chromosome movement during meiosis had been worked out. Walter Sutton and Theodore Boveri noted that the behavior of chromosomes was parallel to the behavior of genes and used chromosome movement to explain Mendel's laws.
They united the knowledge of chromosomal segregation with Mendelian principles and called it the chromosomal theory of inheritance.
According to this theory:
$(i)$ All hereditary characters must be with sperm and egg cells as they provide a bridge from one generation to the other.
$(ii)$ The hereditary factors must be carried by the nuclear material.
$(iii)$ Chromosomes are also found in pairs like Mendelian alleles.
$(iv)$ The two alleles of a gene pair are located on homologous sites on homologous chromosomes.
$(v)$ Sperm and eggs have haploid sets of chromosomes which fuse to re-establish the diploid state.
$(vi)$ Genes are carried on the chromosomes.
$(vii)$ Homologous chromosomes synapse during meiosis and separate to pass into different cells.