984 J. B. GATENBY AND J. H. WOODGER 
though some indications of this have been noted (see 11, 
p- 581), and until such is established we are not justified in 
dismissing the hypothesis of a special ‘ cytoplasmic heredity ’. 
More than this we cannot at present write ; the very function 
of the mitochondria and the Golgi apparatus is not understood, 
and those paths which will lead to this understanding are only 
now being entered. 
UNIVERSITY COLLEGE, LONDON, 
April 12, 1920. 
12. SUMMARY. 
(a) The Middle-piece Golgi Apparatus. 
1. The middle-piece of the mammalan spermatozoon is 
formed from part of the mitochondria of the spermatid which 
become grouped around a central rod or skeleton. Not all 
the mitochondria of the spermatid pass into the middle-piece, 
a certain proportion always sloughs off. 
2. On the middle-piece of many mammalian spermatozoa 
there is a protoplasmic bead which can be seen in the fresh, 
and which, on fixation, stains in plasma dyes. 
3. With formalin and silver nitrate techniques the proto- 
plasmic bead is found to contain a number of argentophil 
platelets or rods, which impregnate exactly like the Golgi 
apparatus of younger sperm cells. 
4. The spermatid of Cavia contains a Golgi apparatus con- 
sisting of an inner core of archoplasm, and a cortical region 
formed of curved plates and rods—the dictyosomes. With 
formalin-silver nitrate techniques, the Golgi apparatus either 
appears as a reticulum, or the whole cortex of the apparatus 
reduces the silver, and then appears homogeneous : with Mann- 
Kopsch techniques the individual dictyosomes are often very 
clearly marked. 
5. At a stage when the spermatid is elongating the Golgi 
apparatus buds off a small part of itself. This part becomes 
