Mitochondria, Golgi Apparatus, and Yolk. 143 



lo the oocyte tlie apparatus is at first juxta-nuclear and 

 eccentric, but later spreads out throughout the egg cytoplasm. 

 The elements of the Golgi apparatus are somewhat filamentary 

 and branched, and possibly take no direct part in the formation of 

 fat or yolk. From our preparations of guinea-pig testis, both 

 by Cajal and the Mann-Kopsch methods, we believe that the 

 mammalian Golgi apparatus, like that of certain invertebrates, 

 consists of numerous semi-lunar plates or rods and not of branched 

 straight bodies as drawn by Hortega. The appearance shown in 

 Text-figs. 1 and 2 of such branched rods is possibly due to the 

 distortion caused by the formalin fixation. In all probability 

 further v/ork will show that the Golgi apparatus in mammalian 

 oocytes is formed of small curved plates and rods which may 

 occasionally join together in chains to produce a reticular or 

 branched appearance. In PL II, figs. 2 and 3, are a sperma- 

 tocyte and a spermatid showing the Golgi apparatus (GA). 



On the Supposed Metamorphosis of Mitochondria 

 INTO Fat Vacuoles. 



Dubreuil {8) and Murray {30) showed that mitochondria could 

 metamorphose into bodies possessing the histo-chemical reactions 

 of fat. The elongate mitochondrium in this case becomes swollen 

 parts of its length, and finally forms one or more separate fat 

 spheres. It may be remembered that in degeneration of medul- 

 lated nerve, the lipin substances in the sheath become changed 

 into fat. The fat globules which appear in mammalian and other 

 oocytes during oogenesis may be formed partly by a metamorphosis 

 of the lipin substance in the mitochondria, but it would be a 

 mistake to consider that the fat of cells is exclusively produced by 

 changes in mitochondria. 



In the case of digestion there seems little doubt that the 

 mitochondria take no direct part in the production in the cells of 

 fat. Food matter containing the latter is acted upon by a lipase 

 which breaks up the fat into glycerol and fatty acid, in which form 

 it passes through the membrane of the intestines, in whose cells it 

 is reconverted into fat. Such fat ultimately becomes distributed 

 by the blood, and is taken up into connective tissue and other 

 storage cells. There seems no reason for disbelieving that oocytes 

 could take up fat in a similar manner, and independently of the 

 mitochondria. 



With reference to the formation of fat in cells, we may give 

 some account of Schreiner's work on the subcutaneous cells of 

 Myxine (39). He describes a most complicated process in these 

 cells ; their nuclei contain a nucleolus or several nucleoli, which 

 bud off smaller bodies, and these become separate as " neben- 



