Tuberculin was invented by Dr. Robert Koch, a German physician and microbiologist, in 1890. **

Tuberculin did not work as a reliable diagnostic tool for tuberculosis because it was found to produce false positive and false negative results. This was due to the fact that tuberculin was a crude mixture of proteins derived from the tuberculosis bacteria, which led to variability in the immune response in different individuals. Additionally, factors such as previous exposure to the tuberculosis bacteria or other mycobacteria could also affect the accuracy of the tuberculin skin test. As a result, more specific and reliable diagnostic tests, such as the interferon-gamma release assays, have been developed to detect tuberculosis infection. **

Horizontal mergers can lead to economies of scale, increased market power, and the ability to eliminate competition. By combining two companies that operate in the same industry, the merged entity can benefit from cost savings and increased efficiency. On the other hand, vertical mergers can result in better control over the supply chain, reduced transaction costs, and improved coordination between different stages of production. This can lead to improved quality control, lower production costs, and increased market access. Both types of mergers can result in increased market share and potentially higher profits for the merged entity. **

In a free market economy, it can be justified to restrict market and entrepreneurial freedom through the requirement for approval in larger mergers in order to prevent monopolies and promote fair competition. Without such restrictions, larger companies could potentially use their market power to stifle competition, leading to higher prices and reduced consumer choice. By requiring approval for larger mergers, regulators can ensure that the market remains competitive and that smaller businesses have the opportunity to thrive. This can ultimately benefit consumers and the overall economy. **