PROCESS OF FERTILIZATION IN THE CRAB 159 
tions than those shown in figures 61 and 62. The diameter of 
the capsule of these spermatozoa is about 3.8 uw and the pseudo- 
podia are sometimes as much as 7 uv long. 
Spermatozoa in the deferent duct 
The mature spermatozoa pass from the tubules of the testis 
into the deferent duct. . The latter is a long, extensively folded, 
tube lined with glandular epithelium. The spermatozoa form a 
common mass when they enter this tube, but the secretion formed 
by its lining flows in among them and separates them into groups. 
The secretion surrounding each group then hardens and so forms 
a membrane, so that finally there are an immense number of 
capsules containing the spermatozoa. These capsules are known 
as spermatophores. In this condition the spermatozoa are trans- 
ferred to the seminal receptacle of the female crab. 
Summary and discussion 
In this study of spermatogenesis in Menippe mercenaria the 
principal points brought out are as follows: 
1. There is a single row of cells which persists on one side of 
the testicular tubule and gives rise to successive batches of 
spermatozoa. 
2. The spermatogonia divide without the formation of a spi- 
reme. The chromatin simply aggregates into chromosomes which 
are then gathered into an equatorial plate. 
3. The maturation divisions follow one another quickly. They 
are preceded by spireme formation and a long period of synapsis. 
4. There also seems to be a relatively long resting stage after 
the nucleus of the spermatid is formed before the transformation 
into the spermatozoon begins. 
5. In the transformation of the spermatid, three structures 
must be considered, namely, the nucleus, the capsule and the 
mitochondrial ring. 
6. The nucleus becomes uniform in consistency, reduced in size 
and cup-shaped. 
