Hello. You did not say what Huxley's lecture the question is about, which makes it impossible for me to give you an exact answer. However, to help you, I will show you ways that will show you how to find the audience that Huxley intended to reach.
First, it is important that you keep in mind that the language used in the words must take into account the age, profession, gender and degree of knowledge of the intended audience. Thus, if the audience intended by Huxley were school children, he must have used clear, simple and direct language, without technical terms and without a refined and elegant language.
The same language can be used with an audience made up of people who are not scientists, but who are interested in what Huxley can say. However, here language can be a little more formal, but still understandable and easy.
If Huxley wants to speak to other scientists, he can use technical and specific terms, a highly refined and normal language and the presentation of specific terms, which are difficult and often subjunctive.
If the audience that Huxley wants to reach are students, he must present a less formal, direct and introductory language, where many concepts are explained.