When the news is released that someone else has published first, Tubbs takes on an "I told you so attitude" and refuses Martin all the benefits he had promised. Nevertheless, it seems almost impossible for the scientist to exist without these institutions for financial reasons. It would be very expensive to create one's own lab facilities and to create the connections needed to publish and "succeed." Even Gottlieb, who hates the commercial world of science more than anyone in the novel, does not leave the institution. Gottlieb is completely against commercialism because he is a perfectionist who becomes angry when the powers that be do not allow him to fully complete his research, for an experiment is not complete until one can understand the "fundamental nature" of what is occurring, and it is only then that the discovery of the scientist can truly be of help. Even so, he even accepts a position as director of McGurk when Tubbs resigns. Furthermore, even Gottlieb is not altogether incorruptible. For, even though he has good intentions (a vision of a laboratory dedicated to "pure science", he does not pas up the opportunity of a directorship.
In a way, people like Tubbs are necessary in the scientific world. The laboratory scientist, himself, does not have the business savvy required to run an institution, as is proven by the failure of Gottlieb's venture as director. And, thus, even if the institutions and institution heads are corrupt and commercial, it is evident that they are necessary. This does not diminish Lewis's critique, it simply complicates the matter, as it is in reality.
The character of Sondelius is important because of his willingness to work for what he believes. He works for free, which even Terry Wickett and Martin Arrowsmith will not do. Perhaps, Sondelius is gratified with other forms of success aside from money. Perhaps he is more content with fame or power, although this would be the pessimistic way of assessing Sondelius's character. Looking at him in a positive light, one might say that he has a true desire to care for his fellow man and to rid the world of disease. Perhaps his desire to venture out into the "tropics" and study different diseases is purely altruistic. Perhaps it is a little of both.