WILL you allow me to make one or two observations upon the remarks made by the writer of the article on the last part of the “Physiological Anatomy and Physiology of Man?” In few words the reviewer has drawn attention to several of the most important points advanced in this part, and for this I feel much indebted to him. But with reference to adipose tissue, he observes that I convey the impression that the adult fat cell “consists merely of an envelope containing oily matter—no mention being made of the fact that by proper treatment a nucleus also can be almost always demonstrated.” This is strange, for I believe I was the first to demonstrate the “nucleus” in the fat cells of adult adipose tissue. In my lectures at the Royal College of Physicians in 1861, I showed specimens illustrating the fact, and in the work reviewed I have endeavoured to show that the so-called “nucleus” (germinal matter or bioplasm) is concerned in the formation of the fatty matter, and in its removal from the fully formed fat vesicle (p. 305) whenever we get thin from the absorption of fat. In fig. 198, plate xx., fat vesicles in various stages of development are represented, the “nucleus” being given in every one, while in fig. 132, plate xv., are shown some fat vesicles in cartilage, the nucleus being seen in every instance. If I have not made this point sufficiently clear in my description, it arises from the circumstance that I desired to leave as much as possible of the general description given by my predecessors in the first edition. In the early part of the chapter the nucleus has not been mentioned, which is to be regretted, but in the latter part, containing the new matter, very frequent allusion to it has been made.