214 a. w. greenwood 



Spermatogenesis of Sarcophilus ursinus. 



Both male and female animals of this species were obtained. 

 The technique followed was the same as in Phascolarctus, 

 viz. fixatives used were Allen's modification of Bouin, and cold 

 Flemming ; this was followed by staining in Heidenhain's i^ron 

 alum haematoxylin. In the testis the same more or less 

 definite layering of the germ cells in the tubules is noted as in 

 Phascolarctus. 



Number of Chromosomes. 



In the female the number of chromosomes was obtained 

 from metaphase plates of dividing follicle cells surrounding 

 the ovum. The number found was fourteen. Of this number 

 twelve are large and the other two are much smaller. These 

 two smaller ones, similar in size and shape, are the sex chromo- 

 somes. The chromosome formula of the female Sarcophilus 

 is therefore 12 + XX (PI. 16, fig. 22). 



In the male chromosome counts were obtained from spermato- 

 gonial plates and first meiotic division stages. 



From the metaphase plates of the spermatogonia! divisions 

 the number of chromosomes was found to be fourteen. Here, 

 as in Phascolarctus, the presence of a small X-chromosome 

 and a minute Y-chromosome, usually in the centre of a circle 

 formed by the twelve larger autosomes, was again noticed 

 (PI. 16, fig. 23). In fig. 24 the spermatogonial chromosomes are 

 dividing or have already divided. Two of the chromosomes 

 as yet show no sign of splitting (PI. 16, fig. 24, a and h). The 

 division of the Y-chromosome is A'ery clearly shown in this 

 figure. 



The chromosome formula of the male Sarcophilus is 

 therefore 12 + XY. 



Meiotic Phase. 



I have made no attempt to follow out in detail the phenomena 

 of the meiotic phase, but stages similar in appearance to those 

 of Phascolarctus are found in Sarcophilus. 



