76 H. B. GOODRICH 



the difficult nature of the material with which he is dealing and 

 are difficult to interpret.^ 



Upon the basis of his studies Brauer, as is well known, has 

 suggested an interpretation of the maturation in Ascaris whereby 

 both divisions are recognized as being equational and so quite 

 at variance with the more generally accepted conception of re- 

 duction. He has found undivided linin threads bearing single 

 granules appearing at a stage which seems to correspond to the 

 post-synaptic pachytene stage of Ascaris incurva; these granules 

 and the supporting threads divide twice forming a doubly 

 cleft thread bearing granules arranged in sets of fours. The 

 threads then shorten to form chromosomes, the clefts represent- 

 ing the planes of division of the chromosomes in maturation. 

 In Ascaris incurva it is found that the thread at an early post- 

 gonial stage preceding that described by Brauer are paired, they 

 are paired as they enter synizesis, they emerge as double threads 

 and later become quadripartite — in other words at no time 

 is there observed a condition of univalence and a subsequent 

 equational splitting which is the basis of Brauer' s contention. 

 The evidence indicates on the contrary that here as in many 

 other classes of animals the chromosomes unite in pairs (side 

 by . side) to separate later, reductionally, in the maturation 

 division. 



Of the more recent workers Marcus ('06) on Ascaris canis 

 presents a somewhat unusual theory of maturation while Griggs 

 ('06) working on the oogenesis of Ascaris megalocephala, advo- 



often intervenes between leptotene and pachyteme stages and of which Mare- 

 chal ('07) speaks as "un precieux element de diagnostic" of this critical stage 

 of transformation. Hertwig, plate 1, figures 9, 10, 11 and Tretjakoff, figures 

 86 to 90 show nuclei similar to the diffuse stage of A. incurva, figure 14. 



* Of work on oogenesis that of Sabaschnikoff ('97) is not sufficiently detailed 

 for comparison. De Saedeleer ('12) has made an exceedingly careful study 

 but without clear results. His figure 49, showing fine threads and a plasmasome 

 at one side, resembles the leptotene stage of A. incurva. Figures 57 and 58 

 show contraction stages. The pachyteme and strepsitene stages are not readily 

 identified. He describes a second contraction stage (figs. 234, 235, 236, 238) 

 which resemble in some degree the stage of massed chromatin threads in A. in- 

 curva (fig. 29). Figure 146 shows a possibly similar method of chromosome 

 formation to that of. A. incurva (fig. 30). 



