NOTES AND MEMORANDA. 319 



known. If, however, we adopt the view recently advanced by Prings- 

 heim, that ferns were originally composed of " Bionten," some of 

 which were sexual and some non-sexual, and which alternate more or 

 less regularly with one another, we must consider that, instead of 

 having acquired a new power, the ferns which rein'oduce by budding 

 represent a case of atavism. 



De Bary gives the name of Apogamy to this substitution of some 

 other form of reproduction in cases where the power of sexual re- 

 production has been lost. This condition is found in all parts of 

 the vegetable kingdom, and occurs in single species whose nearest 

 allies reproduce normally. Apogamy is of three kinds : apogeny, 

 where the function of both male and female organs is destroyed ; 

 apogyny, loss of reproductive power in the female, apandry, in the 

 male organ. 



Chara crinifa is a good instance of apandry with parthenogenesis, 

 that is of regular embryo-formation from an unfertilized ovule. The 

 female of this species is- alone known in northern Europe, yet it fruits 

 abundantly. It has been studied by De Bary in specimens artificially 

 grown in his laboratory ; and there is no doubt that here it is not a 

 question of the partial suppression but of the total loss of the male 

 organs. In ferns we have the best instances of a substitution of a 

 shoot for the normal sexual growth. To the same category belong 

 some of the mosses usually called sterile, that is destitute of capsular 

 growths. In the mosses, however, it is a question not yet settled 

 whether there is a total loss or only a partial suppression of sexual 

 reproduction. 



In Funkia and Allium fragrans, in the seeds of which Strassburger 

 discovered adventive embryos, we have something similar to the 

 apogamous ferns ; first, in the presence of apparently regularly formed 

 but f unctionless female organs ; secondly, in the presence of apjia- 

 rently active pollen; and, thirdly, in the substitution of adventive 

 embryos for the regular embryo-formation. Citrus and Ccelebogyne, in 

 which Strasburger also found adventive embryos, probably belong to 

 the same class as Allium and Funkia, as may also species like 

 Euonymus latifoUus, many ArcUsice, &c., in which polyembryony often 

 occurs. To these are to be added the numerous species, varieties, and 

 races of cultivated plants which rarely produce seeds, but instead 

 have a correspondingly richer reproduction by shoots. If, as seems 

 tolerably certain, sexual reproduction is requisite to the constant 

 propagation of species, we must regard apogamy as a degenerate con- 

 dition, in which the conditions of propagation are imfavourable. In 

 this connection, however, we must not overlook the fact that in species 

 with budding or non-sexual reproduction this oflspring is produced in 

 surj)assing profusion.* 



Apogamy in Isoetes. — The phenomenon of apogamy appears, 

 according to the statement of K. Goebel,-j- to extend also to Isoetes. 

 In two species, I. lacustris and echinospora, he observed, on a large 

 number of specimens, that both macrospoiaugia and microsporangia 



* ' Amer. Jour. Sci. and Arts,' xvi. (1878) 401. 

 t ' Botauisclie Zeitung,' xxxvii. (187i.») 1. 



