266 THOS. H. MONTGOMERY. 



probable that one of these divisions is reductional. Schockaert, 

 for the ovogenesis of TJiysanozoon, finds also a reduction division, 

 in contradiction to the earlier work of Van cler Stricht. Finally, 

 Carney's earlier work speaks very strongly for the occurrence of 

 reduction divisions. 



It is then very humorous to read in a recent paper by Meves : 

 " Ich fur meine Person halte es aber, heute mehr als je, fur 

 gerechtfertigt, das Vorkommen sogenannte Reduktionsteilungen 

 zu bezwcifeln." Herr Meves has the right to hold any opinion 

 he pleases, but he will soon find himself in the small minority 

 where dogmatic assertion takes the place of fair-mindedness. 

 As the pupil of Flemming, Meves must stand by his teacher, to 

 the effect that there occur only equational divisions. Herr 

 Meves has had very little experience in the field of the phe- 

 nomena of maturation, though he has clone excellent work in the 

 study of the formation of the spermatozoon, and in his paper on 

 the spermatogenesis of Salaniandra overlooked all the phe- 

 nomena which are decisive in regard to a reduction division. I 

 might add, " ich fur meine Person halte Herrn Meves' Resultate 

 unbewiesen zu sein." 



In the light of the recent work it becomes apparent that " het- 

 erotypic " division is synonymous with "reduction" division ; it 

 is heterotypic in being the only mitosis in the germinal cycle in 

 which entire univalent chromosomes are separated in metakinesis. 

 This explains why the shape of the chromosomes in this mitosis 

 differ from all other mitoses ; if it were an equation division, why 

 should its chromosomes differ so markedly from those in other 

 equation divisions? "Transverse," "reduction" and "hetero- 

 typic" divisions express the same phenomenon in different words, 

 and the nail is driven home when the facts are so clear in am- 

 phibian spermatogenesis, in the very cells which were held to 

 disprove the occurrence of reduction mitoses. 



In my paper on Pcripatns I proved that the bivalent chromo- 

 somes are produced by the union end to end of every two univa- 

 lent chromosomes, and not by a splitting of a chromatin spirem 

 into half the normal number of segments. This has since been 

 found by several observers to be the case for other objects. 

 Then in a paper. "The Germ Cells of the Metazoa," I showed 



