NOTES AND MEMORANDA. 



445 



Now wo should insist that since the result is "a true embryo" 

 (equivalent in structure, position of radicle, and ultimate growth to 

 the normal embryo), and not a bud, parthenogenesis is the correct 

 term ; and the very interesting and important conclusion attained is, 

 that parthenogenesis results, not from the development of an un- 

 fecundated embryonal vesicle, as was supposed, but from the develop- 

 ment of other and extraneous cells into an embryo ; also that it is not 

 very rare, since the adventitious or supernumerary embryos of various 

 seeds are cases of this parthenogenesis. 



Not the least interesting consideration is, that we have here a 

 counterpart of what De Bary terms apogamy, instead of an analogue 

 of it. Apogamy is a vegetative prolification from what should normally 

 result in the product of sexual rej)roduction. Parthenogenesis proves 

 to be the inverse of this, a vegetative production in the ovule of the 

 normal result of sexual reproduction, viz, the embryo. And, finally, 

 we have in these two modes, taken together, what was quite to be 

 expected — a manifest and significant rendering of the hiatus between 

 vegetative and sexual reproduction which Mr. Darwin may turn to 

 account. 



Some applications of this new knowledge may be made. It is 

 quite possible that more embryos than we are aware of may be adven- 

 titious. Kather more than a year ago an abstract was given in the 

 ' American Journal of Science and Arts,' of Mr. Francis Parkman's 

 interesting paper on the hybridization of lilies. It may be remem- 

 bered that the greater part of his hybrids exactly reproduced the 

 female parent. The explanation suggested by him, and which he 

 refers to in his paper, was that those plants were not really hybrids 

 at all, but were from embryos originated without male influence. 

 What then seemed the least improbable explanation, would now appear 

 to be the one altogether probable.* 



B. CRYPTOGAMIA. 



Luerssen's Handbook of Cryptogamic Botany. t — The crying 

 want so long felt by all botanists of a good handbook of cryptogamic 

 botany, brought down to our present state of knowledge, is at length 

 supplied, as far as German readers are concerned, by the excellent 

 book before us. Though the work is designed in the first place for 

 pharmaceutists, and is intended to deal especially with pharmaceutical 

 products and their sources, this programme is far exceeded in the present 

 volume. Starting from the classification of Sachs in the fourth 

 (German) edition of his ' Lehrbuch,' the author takes every class and 

 order of Cryptogams in succession, and supplies the reader with an 

 accurate, succinct, and at the same time sufficiently full account of the 

 morphology, physiology, and life-history of each. The result is a 

 thick volume of 657 pages, with 181 admirable woodcuts, many of 

 them new. It is easy to criticize Sachs's classification in many of its 



* 'Am. Journ. Sci. and Arts,' xvii. (1879) 334. 



t ' Medicinisch-pharmaceutiscbe Botanik : zugleicli als Haiidbuch der ey.ste- 

 matischen Botanik, fiir Botaniker, Aerzte u. Apothcker.' Bearbeitet von Dr. 

 Chr. Luerssen. 1 Band, Kryptogamen. Leipzig, 1879. 



