No. 526] SEXUAL REPRODUCTION IN ANGIOSPERMS 615 



tubingense II. Wklr. (S. nigrum L. -f S. lycopersicum 

 L., 1908). For a detailed description of the plant the 

 reader is referred to the original publication. 1 That the 

 conditions under which such a graft hybrid is produced 

 arc very rarely fulfilled, is seen in the fact that from the 

 268 graftings made by Winkler in 1908, 3,000 adventi- 

 tious shoots were developed after decapitating the graft 

 in the manner described, and of these 3,000 the vast ma- 

 jority were specifically pure; five were chimeras, and 

 one the hybrid referred to. Now the all-absorbing ques- 

 tion for the cytologist is: By what means are parental 

 characters transmitted in cases of this sort? Of course 

 speculation is futile until the histological facts are 

 known, but, assuming that such shoots are real hybrids, 

 two guesses may be offered. There may have been (1 ) 

 a migration of nuclei from cell to cell and their subse- 

 quent fusion, as in certain fern prothallia developing 

 apogamous sporophytes, or (2) the hereditary transmis- 

 sion may have been accomplished by cytoplasmic union 

 between cells, or by some sort of enzyme action. 



It is highly probable that these remarkable adventi- 

 tious shoots are not true hybrids, but mere chimeras. 



In a personal communication, Dr. Winkler has very 

 kindly informed me that seeds of li Solanum tubingense" 

 produced pure nightshades (Solatium nigrum), and 

 those of "Solarium proteus" pure tomatoes (Solatium 

 lycopersicum). 



The fact that seeds of "Solanum tubingense" pro- 

 duced pure nightshades seems to be conclusive evidence 

 that the structure in question is not a hybrid, but merely 

 a remarkable chimera. Strasburger ( '09) has just pub- 

 lished the results of a histological study of the tissues 

 formed at the juncture of stock and scion in grafts of 

 Solanum nigrum and Solatium tgcopersicum, and he re- 

 ports that neither nuclear migrations from one vegeta- 

 tive cell to the other nor nuclear fusions in any of these 

 cells were observed. These results are in accord with 

 the same author's cytological studies on other supposed 



l Ber. d. DeuUch. Bot. OeselUeh., 26a: 596-608, 1908. 



