1890.] [Ryder. 



bodies and sperinatogenesis), and, secondly, as the results of their union 

 as complementary bodies through which a new development is initiated. 

 Their reciprocal saturation of each other also prevents polyspermy and is 

 self-regulative, just as all of the processes of development will ultimately 

 be found to be, and as we have seen good reason for believing must be the 

 case in respect to the polar bodies. 



Finally, on our hypothesis it may be said that the chromatin and cyto- 

 plasm in the egg bear a certain proportion to each other, regulated in the 

 ovary. The effort to adjust this relation further after the ovum is free 

 (usually) ends in the expulsion of the polar bodies, which represents an 

 effort at the production of male cells, since the egg as a protovum is 

 invariably the prelude to the production of spermatozoa. The ovum pre- 

 cedes the spermatozoon in the order of time, and the latter must be pro- 

 duced from the former. Protogyny is, in the widest sense, therefore 

 universal, since it is only ova-like bodies which can break down into 

 spermatozoa in which chromatin preponderates. But this may be further 

 qualified by the statement that protogynous tendencies greatly developed 

 must finally themselves lead to the development of an ovum with a large 

 cytoplasmic field. Or, in other words, a condition is reached in which 

 great cytoplasmic specialization is attained, so that the expulsion of the 

 polar bodies may be regarded as the expiring effort of protogyny to pro- 

 duce spermatozoa. 



If this is so, why do not all ova develop parthenogenetically ? Simply 

 because these spermatic elements polar bodies are not completely ma- 

 tured or developed, and while the transmitted energy of growth is insuffi- 

 cient. The remaining body with its reduced chromatin is now, however, 

 the equivalent of a spermatozoon but with an enormous cytoplasmic body, 

 It is complementary to the male element in that it is physiologically recep- 

 tive, and food through karyokinesis for further processes of segmentation. 

 But how about parthenogenetic ova ? Why do these develop and why do 

 some of these develop two polar bodies? Here we often, if not always, 

 have, as already supposed, a greater momentum of growth, with frequently 

 a smaller mass, protogyny is not so markedly developed, and the tendency 

 towards maleness and cleavage is therefore inherently greater. If now 

 new relations or rather want of former modes of nutrition of the cyto- 

 plasm supervenes after oviposition, the momentum of growth tending to 

 segmentation, received from the parent even after the expulsion of the 

 polar bodies, is still sufficient, so that the so-called female pronucleus is 

 able to proceed under these new conditions to take possession of the cyto- 

 plasmic field and initiate normal development under new and independent 

 conditions, through segmentation, leading to the formation of an embryo. 

 If these views are correct, parthenogenesis is the vanishing point of male- 

 ness and femaleness, yet, in some cases, its energy is so great that it 

 sometimes, even then, ends in maleness as seen in the development of 

 drones amongst bees, thus illustrating still further the tendency in some 

 cases to run down to the male condition. 



