The mutation theory; experiments and observations on the origin of species in the vegetable kingdom . loped its stem. Assoon as this had definitely split, and just before the cotyl-edons were about to fall awayI dried this specimen in orderto keep and photograph it. It is obvious that such twinsdo not belong to the tricotyl-ous race, that is to say, thattheir anomaly is due to someother elementarv they should not becounted when recording theseedlings, nor be used as seed-parents. But as their naturecan only be determined for cer-tain in some cases, it is not al-ways possibl
The mutation theory; experiments and observations on the origin of species in the vegetable kingdom . loped its stem. Assoon as this had definitely split, and just before the cotyl-edons were about to fall awayI dried this specimen in orderto keep and photograph it. It is obvious that such twinsdo not belong to the tricotyl-ous race, that is to say, thattheir anomaly is due to someother elementarv they should not becounted when recording theseedlings, nor be used as seed-parents. But as their naturecan only be determined for cer-tain in some cases, it is not al-ways possible to take this pre-caution ; and the fact that thehereditary values obtained fromtetracotylous individuals aresometimes worse than thosefrom the corresponding trico-tyls may in part be due to thiscircumstance. For the rest tetracotyls donot in any essential respect be-have differently in inheritancefrom the tricotyls. From theirseeds are produced, besides the atavists, mainly tricotyls,with hemi-tricotyls and tetracotyls in the usual dimin-ishing proportions. My tricotylous half race of Scvopliu-. Fig. 72. Amarantus specio-sus. Forking of a stemof a tetracotylous plantwith two leaves in thefork which have growntogether dorsally. Thefigure shows also theiraxillary twigs. TricotyIs, Ucmi-tricotyls, and Tcfrocotyls. 363 laria nodosa produced, in the harvest of 1894, a meanof 2% and a maximum of tricotyls per harvested the seeds from two tetracotyls and ol^ and 3% tricotyls. Amongst the 2000 seedhngswliich these cultures contained, there were 30 tricotyls,3 hemi-tricotyls and only 2 tetracotyls. On the other hand a tetracotylous plant of Aspcrulaa-ziirca gave 7% and the corres]:)onding tricotylous seed-]:)arents only 2%, in 1892. Of this 7%, there were 5%tricotylous, 1% tetracotylous, and 1% bred tlie tetracotyls of Aniarantiis speciosus for twos^enerations, in 1893 and 1894. In the summer of 1893,9 tetracotylous plants were left to f
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