The Spermatogenesis of the Opossum (Didelphys 
virginiana) with special reference to the Accessory 
Chromosome and the Chondriosomes. 
By 
H. E. Jordan. 
(From the Anatoruical Laboratory of the University of Virginia.) 
With 2 fignres in the text and plates I — III. 
Contents. 
Page 
I. Points of Primary Interest 42 
II. Material and Methods 42 
III. Spermatogonia — Diploid (duplex) Chromosome group 42 
IV. Interstitial Cells 43 
V. Primary Spermatocyte (Auxocyte) — Growth Period 43 
a) Resting phase (interkinesis) — The chromatin (chromosome) nucleolus 43 
b) Synizesis (contraction phase) and synapsis (bouquet stage) .... 44 
c) Centrosphere (idiozome) 46 
d) Late postsynapsis. Origin of chromidia (mitochondria; chondriosomes) 47 
e) Prophase of first maturation division (reductional) — Haploid (simplex) 
chromosome group 49 
f ) Metakinesis 49 
VI. Secondary (dimorphic) Spermatocytes 50 
a) Resting phase 50 
b) Second maturation division (equational) — ILemioid chromosome group 50 
VII. Spermatids (dimorphic) 51 
VIII. Sertoli Cells (Trophocytes) 52 
IX. Formation of Spermatozoa 52 
X. Suinmary of Results, Review of Literature and Discussion respecting ... 55 
a) Accessory chromosome 55 
b) Synizesis and synapsis (telosynapsis) 56 
c) Chondriosomes (chromidia?) or mitochondria 58 
d) Mature Spermatozoon 70 
Foot-notes 76 
Literature 78 
Description of Illustrations 83 
