SPERMATOGENESIS OE NORMAL AND OF 
HYBRID PIGEONS. 
MICHAEL F. GUYER. 
INTRODUCTION. 
The present study on the spermatogenesis of normal pig¬ 
eons is based largely on material obtained from two species, 
viz: Colvmba livici domestica, the common pigeon, and Turtur 
risorius, the ring dove. Other species were studied for com¬ 
parison. The particulars of the hybrid material will be given 
in detail in the latter part of this paper. 
A description of the various phases undergone by the germ 
cells in their transformation from spermatogonia to mature 
spermatozoa is all that has been attempted in the present paper. 
It was intended originally to investigate also the origin of the 
spermatogonia and of the supporting or Sertoli cells, but it 
vpeedily became evident that such a study is a complicated 
problem in itself which must be postponed for the time being. 
On account of the comparative ease of manipulation and the 
abundance of material that can be secured at any time, the 
pigeon is in some ways well adapted to the study of spermato¬ 
genesis, but the small size of the cells makes a very high micro¬ 
scopic power necessary to obtain satisfactory results, and even 
then the cytoplasmic structure is insufficiently disclosed. 
So far, it seems that no investigations upon the spermato¬ 
genesis of the pigeon have been recorded. A few scattering 
observations have been made upon the spermatozoa, but the 
subject has been, in the main, untouched. Moreover, there has 
been practically nothing done toward studying the genesis of 
the germ cells in hybrids of any kind, although this field, from 
the very nature of the case, would seem to be an extremely 
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