Progeny Size — 123 — Pyridoxine 



is divisible into a number of adjacent "gene centres" arranged 

 in linear order along the axis of the chromosome, cf. Episome, 

 Chromogene, Cytogene, Genosome. 



Protozygote. — Pearson's term for an organism homozygous 

 for a particular dominant gene. See AUozygote. 



Provenance. — The source, or place of origin, of any parti- 

 cular lot of seed. 



Proximal. — That part (of a chromosome) which is nearer 

 the centromere than any specified other part. 



Pseudapogamy. — The replacement of amphimixis by the con- 

 jugation of two ova or of an ovum and a nucleus of somatic 

 origin, or of two somatic nuclei. 



Pseudaposematic. — Pertaining to mimicry in which the warn- 

 ing coloration of a noxious type is the pattern which is copied. 



Pseudapospory. — The mitotic formation of a diploid spore. 



Pseudoalleles. — Genes which appear to be allelic to each other 

 by reason of their being closely linked. Such genes are said 

 to show Pseudoallelism. 



Pseudodominance. — Mock-dominance, q.v. 



Pseudofertility. — The increase in fertility which sometimes 

 results from pollination at the late bud stage in cases where, 

 owing to incompatibility, such pollination would be ineffective 

 or almost ineffective when carried out on the open flower. 



Pseudogamy. — Diploid parthenogenesis in which the partheno- 

 genetic egg develops into an organism. Often such develop- 

 ment is stimulated by the presence of a male gamete but 

 fertilization does not occur. 



Pseudomitotic. — Diaschistic, q.v. 



Pseudomixis. — Fusion between vegetative nuclei, or between 

 cells which are not true gametes, leading to embryo formation. 



Pseudo-reduction. — The halving of the chromosome number 

 which appears to occur when pairing takes place. 



Pseudova. — Parthenogenetic 'ova' capable of further develop- 

 ment without fertilization. 



Purebred. (Animal breeding). — An animal which is the des- 

 cendant, in all lines of its ancestry, of individuals of the same 

 type as itself (cf. Winters). 



Pure Line. — A strain, the individual members of which are 

 genetically pure as a result of continued in-breeding or self- 

 fertilization or through other means. 



Pycnosis. — A moribund nuclear condition in which all the 

 chromosomes fuse in a single mass. 



Pyridoxine. — Vitamin Bg. 



