Oconrroneo of Fat. 403 



in stiKlyiiig fine droplets Scarlet red is somewhat better since it 

 leaves the protoplasm colorless. Sudan sometimes stains protoplasm 

 to a considerable degree. Sudan as well as Scarl(>t red will stain 

 fat droplets of any size an intense red when allowed to act an hour 

 or more. 



Distribution of fat i)i the tissues of the fwtus. 



In the calf there are no rounded fat cells present until about the 

 20 em. stage or later ; but fat droplets are found in the various 

 tissues long before this period. 



Keinath (18) studied some of the musculature and cartilage of 

 calf foetuses. In a 3.5 cm. fcctus, a longitudinal section through 

 the musculature of the anterior extremity shows fine fat droplets in 

 masses or in rows between the fibrilla?. Individual fine fat droplets 

 occur in the cartilage cells. In a 4.5 cm. foetus, fat droplets are also 

 present inside the muscle fibers and in the cartilage cells. A 9 cm. 

 and a 12.5 cm. foetus each showed fat in the fibers of the pectoral 

 muscles, but none was found in the heart muscle. Two foetuses, 

 20 cm. and 40 cm. long respectively, contained no fat in the pectoral 

 muscles. The same observer found no fat in the musculature of 

 a 1.5 cm. pig. 



]\Iy owm observations are as follows: 3 em. foetus (two specimens). 

 No fat was found in muscle, liver, skin, or cartilage. This finding 

 does not necessarily contradict the observations of Keinath — the fat 

 content of tissues both foetal and adult is subject to considerable 

 variations. 



4.7 cm. foetus. The liver shows fat droplets in the cells near 

 the larger veins. No fat w^as found in the cartilage of the vertebrse 

 or that of the femur. The musculature of the thigh and back con- 

 tained no fat. 



7 cm. foetus. The hepatic cells are loaded with large and small 

 fat droplets (Fig. 1). The fat is more abundant near the veins. 

 The genital gland contains a large amount of fat in the interstitial 

 cells. The muscles of the neck, thigh, and back w^ere studied for 

 the presence of fat. Many muscle fibers in each situation contain 

 fine fat droplets in between the fibrillse. There is usually one fat 



