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THE GUIDE TO NATURE 



some phase of parthenogenesis and 

 states that it would be reasonable to 

 expect marked uniformity in size, leaf 

 characters and season habits among 

 the off-spring., 



In this connection I would like to 

 report briefly upon certain partheno- 

 gens which resulted from my attempts 

 at hybridizing across considerable dis- 

 tances. In none of these parthenogens 

 has there been any evidence of re- 

 versal to ancestral type as yet. The 

 three photographs which are here pre- 

 sented represent a characteristic dis- 

 parity in size among parthenogens 

 from one parent The photographs are 

 of three parthenogenetic butternuts 

 Juglans cinerea. They were made by 

 subjecting pistillate flowers of the but- 

 ternut to the influence of pollen from 



BUTTERNUT PARTHENOGEN. 

 Height twenty-two inches. 



the bitternut Carya minima and repre- 

 sent three seasons' growth under like 

 conditions of cultivation, in a field 

 with uniform character of soil — a shal- 

 low gravelly glacial till. The height 

 of these three young trees is approxi- 

 mately 22 inches, 33 inches and 57 

 inches respectively. They were all 

 photographed with the camera placed 

 at three yards distance. Similar dis- 

 parity in size has been observed among 

 some of my parthenogenetic chestnuts, 

 hickories and butternuts, with or with- 

 out male "influence." 



When some cell of the ovule of a 

 plant of one genus is stimulated into 

 activity by the pollen from a plant of 

 another genus, I have termed the phe- 

 nomenon "stereochemic parthenogen- 

 esis" temporarily, as a basis for one or 

 more working hypotheses. We assume 

 that each protoplasmic mass retains 

 its fixed molecular identity, but that 

 forces acting over molecular distances 

 excite the protoplasm of an egg into 

 segmentation (without fusion of two 

 opposite sex masses to form a gamete). 



What is the nature of the force? Per- 

 haps we may speculate as follows: 



The protoplasmic mass in the form 

 of a cell with a cell membrane may 

 respond to influences depending upon 

 the semi-permeability of that cell mem- 

 brane, and this may relate to osmosis 

 (an expenditure of force) at work upon 

 the cell. Osmosis may depend upon 

 the presence of hygroscopic sugars and 

 organic acids of different characters in 

 pollen tube and egg. Enzymes which 

 are not isomeric may act over greater 

 than molecular distances, and furnish 

 a force for stimulating protoplasm of 

 the egg into activity. 



A still more distant speculation, but 

 one worthy of consideration according 

 to the electron theory, includes the 

 idea that enzymic action may liberate 

 force that is electrical in its nature, 

 and we might then have an exchange 

 of ions at the site of a cell membrane 

 (difference in potential). The reason 

 for the assembling of anions upon one 

 side and kations upon the other side of 

 a cell membrane would again depend 

 upon the semi-permeability of that 

 membrane. The protoplasm encom- 

 passed by the cell membrane is an elec- 

 trolitic conductor and might respond 

 to stimulation from forces at the site 

 of a cell membrane, by going into seg- 

 mentation. Whatever the nature of 

 the stimulation of a given egg cell, the 

 result might be as follows : 



The egg goes into segmentation ac- 

 cording to diploid system, if fusion oc- 

 curs between any two cells of the em- 

 brvo sac. In case of segmentation from 

 cell nuclei without fusion, we would 

 have haploid segmentation. With dip- 

 loid segmentation the progeny of a 

 "stereochemic partheno^en" would pre- 

 sumably be fertile. If the fruit results 

 from growth of egg or from one of the 

 other embryo sac nuclei without fer- 



