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HERBERT H. BROWN. 
and his account of the process agrees very closely with that 
which I have given, but he does not describe the separation of 
the globules of residual protoplasmic material which takes 
place when the development is nearly completed. He describes 
the accessory coi’puscles, both in the seminiferous cells and in 
the nematoblasts, and suggests that they may represent the 
polar globules of the ovum. 
Swaen and Masquelin, in the 'Archives de Biologie J for 
1883, give the results of their investigations upon spermato- 
genesis in the Selachians, the Salamander, and the Mammal. 
Their account of the process in the mammal was taken from a 
study of the testis of the Bull, and agrees in many particulars 
with that of Benson. These observers give an acccount of 
the manner in which the continual production of succeeding 
generations of spermatozoa is kept up in the tubule, which 
presents some resemblance in principle to the view of the 
process which I have taken, though differing from it in detail. 
They call the small cells of the outer layer — the germinative 
cells of Sertoli and Benson — while they are in the resting 
condition “ inactive male ovules.” These cells passing into the 
kinetic condition become the active male ovules, and gradually 
leave the wall of the tubule. Before long each cell divides 
into two bv karvokinesis in a radial direction : the external of 
* i J 
the two cells becomes embedded in the outer layer, and passing 
into the resting condition, becomes an inactive male ovule, 
which repeats the process in the succeeding cycle. The other 
cell, which is internal, increases in size, and finally divides by 
karvokinesis into a group of cells, the “ spermatogemme.” 
The cells of which the spermatogemme is composed are 
called spermatocytes, and afterwards, when they have obvi- 
ously begun the process of development into spermatozoa, 
receive the name of nematoblasts. The nematoblasts become 
attached to the supporting cell without being first free in the 
tubule, for the inner extremity of a supporting cell which has 
discharged its spermatozoa fuses with the intercellular material 
of the spermatogemme. 
The account which I have given of the origin of the growing 
