No. 626] GIGANTISM IX NICOTIAN A TABACUM 231 



then it is quite as probable that all the gametes in a single 

 blossom, or the gametes produced by all the blossoms of 

 a normal plant, may become so modified. Honing 's ob- 

 servations at least would indicate that this does occur. 



In those instances where an occasional Mammoth ap- 

 pears in the progeny of a normal plant, it is usually as- 

 sumed that the change responsible for the Mammoth char- 

 acter was associated in some way directly with the ga- 

 metes themselves. In those instances where many or even 

 all the plants in the progeny of a nonnal plant produce 

 Mammoths, the question becomes more involved and dif- 

 ficult of interpretation. It is very difficult to see how all 

 the gametes of a normal plant can become simultaneously 

 modified to ]>roduce by their union Manmioth plants, un- 

 less we nssunie that the change take^ place at some stage 

 preceding the development of the gametes. Should the 

 change take place in a mother cell of the anther preceding- 

 tetrad formation, /. e., by the addition or subtraction of 

 some factor in the chromosome material, it is reasonable 

 to suppose that the four pollen grains resulting from the 

 division of this mother cell may l)e similarly affected, and 

 bear the ^raitiinotli character. It is i)ossil)le, however, 

 that the cluniuc may tnke plnco \-ory much earlier, so that 

 a part or cwn all the si.(.ro--eii(>iis cells will be al¥ected. 

 If this condition occm rrd, ii is ensy to see how great num- 

 bers or even all the pollen trains arising from their di- 

 vision would bi'iir the Mammoth character. Since the 

 development of the mega>porangium is in every way par- 

 allel to the develoi)ment of the microsporangium or an- 

 ther, similar changes would affect one or more egg-cells, 

 depending upon whether the change responsible for Mam- 

 moth character took place immediately in the egg-cell it- 

 self, in the mother cells, or very nmch earlier, so that all 

 the sporogenous cells, and hence all the egg-cells arising 

 from tliem, are affected. Such chanu-es affectinu" ii'reat 

 numbers oi- all the u-anu^o- in a -ina'lc llowci-. or even 

 in the entire tlowci- liea<l it-rll'. would pro(hn-t' the i»he- 

 nomenon of a nioi'e or less complete actiuiienient ot' Mam- 



