354 THOS. H. MONTGOMERY, 



Platner, Lee, and v. Erlanger are so similar to my own results, 

 that I feel that some true homology must obtain, — that it cannot be 

 a mere coincidence but must be the expression of some common 

 underlying relation. There is one case which seems to be an ex- 

 ception. Hermann (1891) figures a first spermatocyte of Proteus in 

 which the angles of the bivalent chromosomes are directed towards 

 that pole of the cell where the sphere lies (i. e. towards the distal 

 pole of the nucleus). This observation does not agree with those 

 of Kingsbury (1899) and Eisen (1900) on other Amphibia; and 

 Meves (1896), in the left hand cell of his fig. 47, tab. 4, of a 

 spermatocyte of Salamandra, shows those chromosomes which are of 

 a horseshoe shape with their angles or bends directed away from the 

 pole of the nucleus nearest the idiozome sphere. Meves has demon- 

 strated that the idiozome sphere in the salamander wanders to the 

 equatorial pole of the cell (the distal pole mihi); perhaps Her- 

 mann's figure of the Proteus spermatocyte represents a stage before 

 such a wandering takes place, and if that be so, then this case would 

 be no exception to the rule I have drawn of the relation of the po- 

 larity of the nucleus to that of the cell. 



4. The Synapsis Stage. 



In Peripatus there occurs in the anaphase of the last spermato- 

 gonic division a particular stage, the synapsis, when the union of 

 univalent chromosomes into pairs is effected. I had previously de- 

 scribed this stage for Pentatoma : and have found it in a beetle {Har- 

 palus), in the cricket (Gryllus), and in the spermatogenesis of the 

 Copepod Calanus. 



In most of the objects in which this stage is marked it can be 

 sharply distinguished as a particular stage by the dense grouping of 

 the chromatin threads near one side of the nuclear cavity where they 

 form an inextricable mass. But in other forms, as in Peripatus^ this 

 grouping may be very much less dense, and this is the case also in 

 Salamandra (Meves, 1896). Moore (1895) introduced the term 

 "synaptic phase" for that stage in Selachii when the reduction in number 

 of the chromosomes is effected. It has been described for Ascaris 

 most fully by Brauer (1893), also by Hertwig (1890), and Sabasch- 

 NiKOFF (1897); for Biaptomus by Ishikawa (1893); for Anasa by 

 Paulmier (1899); by Woltereck (1893) for Ostracods; by Calkins 

 (1895) for Lumbricus; and ;by Henking (1890) for Pyrrhocoris. In 

 Amphibia it would seem to be most plainly marked in Desmognathus 



