968 Transactions of the Ameohcan Institute. 



frequently prcseuted before thunder, from the air being more than 

 ordinarily charged with electricity; or it may occur in the spring, 

 during the presence of ozone, which seems to promote the germi- 

 nation of long sown seed. 



The cross having been performed, the next anxiety will naturally 

 be to j&nd out whether it has taken. Almost all experimenters have 

 noticed that soon — say from six to ten days — an alteration is 

 observed on the stigma and style. On finding the viscous matter 

 dried up, and the style beginning to shrivel, it would be natural to 

 conclude that all is right, and that the fertilizing pollen has noAv 

 passed down into the ovar}'-, and in some cases this conclusion may 

 be right; but these appearances are deceptive, especially if the style 

 maintain an erect position. The various instances of failure noted 

 by Wichura are as follows: a. The organs submitted to hybridiza- 

 tion soon wither, but do not in all cases s'feon fall ofi". * b. Tlie 

 t>varies swell and ripen, but do noi contain a trace of seed. 

 6. The ovaries may seem filled, having in some instances the small 

 |;irotuberant swelling outside, as if seeds were within, and yet no 

 seed be there, d. Seeds are present, but small, languid and iuca- 

 j;iable of germination, e. Seeds apparently perfectly developed, 

 but do not germinate, f. Seeds germinate, but the young plants 

 are weak, and wither in a short time, dying ofi" oftentimes after 

 developing the seed leaves. Wichura further says: "When both 

 parents belong to the same species, we cannot tell what part the 

 male and female parent take, respectively, in the formation of the 

 progeny. But dissimilar factors are united in hybrids, and an inter- 

 mediate form' is the consequence. The products which arise from 

 a reciprocal crossing in plants, unlike those which are formed in 

 animals, are pefectly alike. It is of no consequence which is the 

 male and which the female parent. It is, therefore, a mathematical 

 necessity that the pollen cells must have just the same part in the act 

 of generation as the ovules." To the absolute correctness of these 

 dogmas the lecturer demurred, and proceeded to describe various 

 experiments made by him in crossing, which furnished exceptions 

 to the rule of reciprocity, and where such reciprocity does hold, 

 of the exact similarity of the progeny. 



In experiments illustrating his view of sympathy and antipathy, 

 the lecturer had found instances so inexplicable that he could only 

 concur with Darwin, who, in his paper • on the existence of two 

 forms in the genus linum^ after summing up the good gained by 

 the inevitable crossing of dimorphic flowers, concludes from these 



