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curs wheu the spores are fonned, which may be many thousands of cell 

 generations renioAed from the time in ontogeny when eggs and sperms are 

 differentiated; whiJe in animals the reduction immediately precedes the 

 formation of the gametes. In regard to the chromosomes themselves, the 

 view generally ]irevailing is that each possess a distinct identity or indi- 

 viduality which is maintained throughout ontogeny-, and phenomena per- 

 taining thereto have been presented under the theory of the individuality 

 of the chromosomes. Very recently, however, the idea of individuality has 

 been taken away from the chromosomes and applied to smaller units, sucb 

 as the chromomeres. or better the microscojtically distinguishable granules 

 which make ni» tlie chromomeres. We may call these particles pangens, 

 or select any name which may be convenient and likely of adoption. The 

 writer has expressed liis views on this subject in greater detail in a recent 

 publication, and only a few l)rief statements will be made here, in as much 

 as a fuller discussion is regarded as being too technical for a general audi- 

 ence. The idea of individuality is applied to the chromomeres or the small 

 particles composing them, chiefly because the identity of the chromosome 

 is lost in the restin nucleus. There are no good reasons to believe that 

 a given chromosome always contains the same hereditary qualities in any 

 succession of cell generations. Furthermore, no special importance should 

 be attached to the different sizes of the chromosomes, for, as a rule, one 

 of the most striking ]»lienomena in a dividing nucleus is tlie marked differ- 

 ence in the size of the chromosonit's. These small material particles, or 

 pangens, are responsible for the characters of the individual, although they 

 are not regarded as the immediate characters themselves. They may be 

 roughly compared with ferments, bringing about changes which collectively 

 constitute development, and produce those chemical re-arrangements of 

 which form, color, and so forth, are the visible expression. Fused gamete 

 nuclei, however, do not constitute a chemical union but a mechanical mix- 

 ture. The numerical reduction of the chromosomes is a consequence and 

 a condition ol sexuality. It i-^ probably not a mere halving of the bulk of 

 the chromatin, but a selection and a distribution between dauglitei- cells of 

 structural entities — the pi-iniordia of cliaractors which ;\re handed from 

 one generation to another. The Mendelimi princi|)le shows, if it shows 

 an.vthing worth while, that these units ;\c| iudeixMidently. 'i'he nucleus, 

 therefore, dinvts and controls cellular development, 'i'he outer manifesta- 

 tions known as variation ai'e jivobably (ln(> to \ho inter action of nucleus 

 and cyt(>i)lasm. 



