Tell me the methods of studying cytology and histology, genetics, hygiene and ecology.

In cytology and histology, research methods are divided into: morphological (study of the structure), qualitative, as well as quantitative (conducting experiments to compare parameters). In hygiene, methods are: biological, chemical, physical, sanitary examination, express method, zoohygienic experiment. In ecology, methods are widely used: observation, experiments, building models. To study human genetics, indirect methods are used (biochemical, genealogical, cytogenetic, twin), and for small animal species, the hybridological method of crossing.