APPENDIX I 



Species {continued) 

 EcoTYPE, capable of genetic recombination with other similar units 



within the Eco-species and not suffering from it. 

 Cryptic Species, such as are not distinguishable by external mor- 

 phology. Darlington 1940. 

 Sub-species, a sub-division of a species larger than a supposed Race. 

 Sperm, the Male gamete, v. Egg. 

 Spermatocyte, v. Mother Cell. 

 Spermatogenesis, development of the sperm from its mother ceU. 



Spermatogonium, a cell giving rise to sperm mother cells either directly 

 or by mitosis. La Valette St. George 1876. 



Spindle, the axially differentiated crystalline (or "fibrous") part of the 

 cytoplasm within which the centromeres of the chromosomes are 

 orientated during metaphase and anaphase. Normally bipolar, 

 exceptionally unipolar or multipolar. 

 Spindle Attachment, the position of the Centromere. 



Spiral, a coil of the chromosome, chromatid or chromosome thread at 



mitosis or meiosis. Classified by Darlington 1935 as follows: — 

 External Spiral, coiling which is externally visible when the internal 



coiling is concealed. Includes Relic and Relational Spirals. 

 Internal Spiral, a coil within a single chromatid between prophase 



and anaphase, or at meiosis jointly for two sister chromatids. 

 Major Spiral, the larger internal coil at meiosis. 

 Minor Spiral, the smaller internal coil at meiosis. 

 Molecular Spiral, the coiling within the chromosome thread which 



conditions internal and relational spirals. 

 Relational Spiral, coiling of two chromatids or chromosomes round 



one another. 

 Relic Spiral, the internal coiling wliich survives as external at telophase 



and prophase. 

 Spiralization, the assumption of an internal (but not a relational) 



spiral within the chromatids in mitosis and jointly for two chromatids 



in meiosis. Darlington 1932. 



Spore, a single cell reproducing an organism but incapable of fertihzation. 

 In the higher plants it is a haploid cell produced by meiosis from a 

 diploid and gives rise to a Gametophyte. 



Sporocyte, Spore Mother Cell. 



Sporophyte, an individual of the diploid generation in plants, normally 

 producing the spores. 



419 



