56 H. H. NEWMAN. 



that has reached the mid-period of atresia. Abstriction of the 

 deutoplasm is essentially an act of rejuvenation on the part of a 

 dying cell, in that the still living protoplasm is freed from the 

 burden of the inert by-products of metabolism. The exact me- 

 chanics involved in this purification process can scarcely be 

 determined from the fixed material, but appearances seem to 

 warrant the conjecture that the very fluid deutoplasmic material 

 escapes from the cell membrane by the rupture of the latter and 

 that, with the subsequent closure of the ruptured membrane, the 

 deutoplasm becomes strictly extra-cellular and without effect, 

 except in a secondary mechanical way, upon the living proto- 

 plasm of the germ cell. Freed from its burden the renewed egg- 

 cell rounds up into an approximately spherical form and ap- 

 parently floats in the deutoplasmic fluid. It is of considerable 

 interest to note that a similar abstriction of deutoplasmic 

 material occurs as the initial step of normal development in 

 Dasyurus. Hill shows that this discarded material plays no 

 further part in development but merely occupies any available 

 space within the persistent zona pelucida that is not occupied by 

 the blastomeres. Finally it comes to lie in the cleavage cavity 

 of the blastula and is probably gradually absorbed. In view of 

 the striking similarity in the early history of the deutoplasm in 

 the two species it is difficult to avoid the conclusion that the 

 process, as described for these ovarian ova of the armadillo 

 during atresia, is a close approximation of the first step in normal 

 development, about which we know practically nothing at present. 

 The deutoplasmic fluid, laden with its masses of deutoplasmic 

 granules, usually gives the appearance of a multicellular body, 

 but I am inclined to consider this condition as largely an artefact. 

 It is not improbable that the strong fixing fluids used coagulate 

 this somewhat viscous material in the form of many small 

 rounded masses. In a few cases, as in Figs. 2 and 4, the deuto- 

 plasm is only slightly broken, but in the majority of instances we 

 find advanced fragmentation, as in Figs. I, 3, 5, etc. Whether 

 the deutoplasm occurs in one or many fragments the deutoplasmic 

 granules occupy a central position in the various pieces giving 

 each fragment the illusory appearance of a nucleated cell. 

 These are not however to be interpreted as in any sense true 



