"Owing to the difficulty of dealing with substances of high molecular weight we are still a long way from having determined the chemical characteristics and the constitution of proteins, which are regarded as the principal con-stituents of living organisms"

This quote by Karl Landsteiner speaks with the trouble of comprehending the chemical characteristics and constitution of proteins, which are considered to be the primary elements of living organisms. Landsteiner suggests that due to the complexity of dealing with substances of high molecular weight, we are still far from having a total understanding of proteins. This is likely due to the truth that proteins are made up of various particles, making them challenging to study and examine. In addition, proteins are continuously altering and adjusting, making it difficult to identify their precise chemical characteristics. Landsteiner's quote highlights the intricacy of proteins and the problem of understanding them, recommending that we are still a long method from having a total understanding of them.