i82 PLANT HYBRIDIZATION BEFORE MENDEL 



the pollen cell must have exactly the same share in the conformation of 

 the fertilization product as the egg" 



So far as the writer knows, this is the first complete categorical 

 statement in the literature of plant breeding of such a conclusion 

 as to the behavior of the sex cells in amphimixis. 



One is completely impressed, in reading Wichura's work, with 

 the scrupulous care, accuracy and precision with which his hybrid- 

 ization experiments were carried out. One or two passages in 

 point are interesting. Referring to a case of Gartner's, where ex- 

 ceptional types appeared in the midst of "a greater number of 

 hybrid plants of completely similar types," he says (p. 53) : 



"To judge concerning the here-mentioned exceptional types, without 

 myself having seen them, is scarcely possible. From the relatively lim- 

 ited number of my experiments, which have not yielded the like, I 

 cannot, to be sure, deny its possibility; but here likewise, as above in the 

 case of reversions, there is the suspicion of the existence of a complete 

 disturbance of the experiment, whether that the protection had not been 

 complete, or the pollen utilized for fertilization not pure, or the seeds 

 sown not free from foreign admixture. Whoever knows from his own 

 experience how much care must be observed in order to keep an experi- 

 ment clean, becomes skeptical respecting all results of an experiment 

 which vary from the usual rule, of the correctness of which one has not 

 achieved conviction through his own observations," 



Regarding these and other so-called anomalies as the result of 



crossing, he again says (p. 89) : 



"That concerning all these points and many other disputable questions 

 , , , we know so little has indeed its basis in part in the method hitherto 

 of artificial cross-fertilization, which suffers from the double deficiency, 

 that the care requisite to the correctness of the experiment, through the 

 exclusion of foreign pollen, had not been taken in the first place, and 

 secondly that, although many experiments have been instituted in very 

 different families, nevertheless the individual hybrids have not been 

 bred and observed in sufficient numbers. However, this is imperative 

 throughout for attainment of general results. Only when one has at 

 hand the same hybrids in hundreds of cases, partly from the same, partly 

 from different parents, repeated through different years, only then will 

 one be in a position to separate the essential phenomena of hybridization 

 from the more accidental ones," 



Finally (p. 92), Wichura remarks, expressing the hope that a 

 learned society or an individual with means might repeat his own 

 experiments on a larger scale : 



"The most scrupulous exactness in such case would be indispensable. 

 Failing this, and especially if the possibility of the access of foreign 

 pollen is not completely excluded, then all experiments, the more ex- 

 tensively they are undertaken, only contribute the more to the confusion 

 of the matter. This must be taken to heart," 



