20 H. HAYS BULLARD 



lets are usiuilly supposed to be absent in summer frogs caught in 

 the field. 



Fat droplets have often been overlooked in skeletal nmsele due 

 to the fact that they are so frequently lost in the fixatives employed 

 (formahn) and may often be left unstained by osmic acid and 

 Sudan in. Bell ('11) who employed Herxheimer's Scharlach R 

 on fresh tissue has demonstrated that 'liposomes' occur under 

 normal conditions in aU vertebrate muscle. He states that the 

 number and size of the liposomes vary in different species and 

 individuals and also with nutritive condition. He examined no 

 human muscle. 



The dog, cat (figs. 2 and 3) and rat (figs. 1 and 2) may be men- 

 tioned as examples of animals commonly having a large quantity 

 of fat in their skeletal muscle fibers while the fibers of the ox and 

 the rabbit have considerably less. I think that an extensive 

 investigation might show that fibers of herbivorous animals do 

 not store fat to such a great extent as is the case in carnivora. 



Human skeletal muscle. I have examined some of the muscles, 

 usually diaphragm, pectoral and eye muscles from about twenty- 

 five autopsies and conclude that fat droplets occur constantly 

 and abundantly in normal human muscle. Fat in the diaphragm 

 was present in large amount in about half the cases examined. 

 In two or three cases the droplets in the fibers of this muscle were 

 few in number or possibly absent but I think that this may be 

 attributed to pathological conditions, poor nutrition or to post 

 mortem change. I have never failed to find fat in human eye 

 muscle, usually in large amount. 



Cardiac muscle. I have examined sections from the right ven- 

 tricle of the hearts of about twenty-five dogs and cats, a dozen 

 rats and several mice. Fat in varying amounts was found within 

 the muscle fibers of all these animals. In two dogs only a few 

 small dropk^ts were to be seen, but usually in this animal fat was 

 present in moderate amount. An exceptionally large amount of 

 fat was present in the cardiac muscle fibers of a well nourished 

 rat and of a pregnan,t cat. 



Human cardiac muscle. Of fifteen hearts, fat droplets were 

 present in ten. Two or three of the remaining five were examined 



