342 Transactions of the Society. 



vations recorded were founded. For staining Prof. Dendy's assis- 

 tant, Mr. Biddulph, employed iron brazilin with excellent results ; 

 a few preparations, however, were restained with iron-hsematoxylin. 

 In view of the limited amount of material available for study and 

 certain intrinsic difficulties which made further confirmatory data 

 desirable, I should not have ventured to place on record the fruit 

 of my studies were it not for the fact that Sphenodon is now very 

 rare ; and that some acquaintance with the gametogenesis of the 

 sole surviving member of an extremely archaic stock may prove 

 of considerable interest when our knowledge of reptilian cytology 

 has been further extended. The work of E. Browne Harvey in 

 collecting an exhaustive index of the chromosome numbers of the 

 Metazoa raises possibilities of such signal genetic and systematic 

 interest as to encourage this expectation. In any event, the facts 

 cited may stimulate others to undertake further investigation, 

 should the author be unable to renew the study of this species. 



Owing to the confused state of the terminology employed with 

 reference to the reduction divisions, etc., at Prof. Dendy's sugges- 

 tion the following glossary notes are introduced. The premeiotic 

 phase of nuclear history (Farmer and Moore) comprises all the 

 cell generations characterized by the diploid number of chromo- 

 somes, including thus the oogonial and spermatogonial as well as 

 somatic mitoses. For the different stages in nuclear division 

 Strassburger introduced the terms pi'o-, ineta- and ana^ihase 

 (1884); Haidenhein (1894) added telophase for the processes 

 immediately antecedent to the resting stage, for which Bolles Lee 

 (1912) proposed spiroijhase or interphase. The meiotic phase 

 (Farmer and Moore, 1905) in animals includes the series of 

 nuclear phenomena betw^een the last spermatogonial or oogonial 

 telophase and fertilization or the inception of cleavage ; Flemming's 

 terms for the first and second reduction divisions, the heterotypc 

 and homotype respectively, are still in use. The nomenclature of 

 synapsis, or the means by which the reduction of the chromosomes 

 is effected in preparation for the heterotype mitosis, is entirely 

 modern. Moore originally defined synapsis as the contraction of 

 the chromatin content of the nucleus from the nuclear membrane 

 in the primary spermatocyte or oocyte ; but as the belief has gained 

 ground that this contraction synchronizes with numerical reduction, 

 the term has been used by later writers for the actual pairing of 

 the univalents, although McClung (1905) and Hacker (1909) have 

 since distinguished the former from the latter as respectively 

 synizesis (contraction) and syndesis (pairing). Two interpretations 

 of synapsis have been put forw^ard by animal cytologists : parallel 

 conjugation {parasynapsis or parasyndesis), reduction by the 

 lateral approximation in pairs of the representatives of the pre- 

 meiotic chromosomes; and terminal union {telosynapsis or mcta- 

 syndesis), reduction by the adherence of the univalents end-to-end. 



