TRANSACTIONS OF THE SECTIONS. 143 



having been made of the probably asexual Protophyta, Thwaites' ideutiiicatiou of 

 conjugation with reproduction proper, made in 1848, was meotioued, aud a sum- 

 mary given of the sexual classification of the Thallophytes proposed by Saclis 

 CLehrbuch, 4th edition) aud adopted by Professor Dyer (Quart. Journ. Micr. Sci.), 

 in which they are grouped asProtophyta, Zygospores, Oosporere, and Carposporese. 

 The types Pandonna, Mesocarpus, Spirogi/ru, and Podosplxpra were taken as indi- 

 cating sexual transition between these groups ; and Sachs" description of the essential 

 nature aud elements of sexual reproduction quoted. The difference between the 

 sexes as manifested previous to the formation of the elemental 'sperm' and 'germ' 

 cells was then traced in the various groups, 'being greater and manifested earlier in 

 the more highly organized groups. 



OEdoffonium, Vaiwheria, Phijcomi/ccs, Coleochate, and Nemalion were alluded to 

 in this connexion, and following the pedigree sketched by Sachs (Lehrbuch, 3rd 

 edition) the 'secondary sexual organs ' were traced through the Floridere to the 

 ancestral Cormophyte and to the ' heterosporous Pteridophyta,' near to which he 

 places the Cycadere, the lowest type of Phanerogam. The homology between the 

 sexual organs of Phanerogams and Cryptogams was pointed out, and Tlildebrand's 

 classification of the sexual arrangements explained. 



In this connexion the terms ' apertiflorous ' (open-flowered) in opposition to 

 ' cleietogenous,' 'approximate,' and ' distant,' with anthers near to or remote from 

 the stigma, and ' homostylia,' were proposed by the author for adoption. It 

 was then attempted to br.se the phylogenetic arrangement of sexual forms (the 

 chief subject of the paper) on the law of economy of nutrition, the advan- 

 tageoupuess of cross-fertilization producing dioecism and various intermediate 

 stages from an original hermaphroditism. Dioecism was first traced through 

 monrecism aud moncecious polj-gamy, Frar/an'a, Pume.v, and a reverting sport of 

 Pet/onia fiigida being quoted. The dioecism of the English holly has probably 

 been reached from dioecious polygamy, as in the American forms, through an inter- 

 mediate monoecism ; and the monoeciously or trioeciously polygamous genus Cata- 

 setiim points to the origin of the latter form from the former probably through an 

 intermediate dioecious polygamy. Dioecism may possibly arise also from dimor- 

 phism, which may be monoecious, as in Dianthus carynphylhis and D. plumarius, or 

 dioecious, as in some Primulas. 



Dimorphism probably originates in ' biseriate ' stamens, tiimorphism in ' tri- 

 seriate ; ' but the dioecious dimorphism of Lythrum thyrsifolia would seem to arise 

 from trioecious trimorphism by suppression. Among the Compositre the transitions 

 are easy from the ' equal polygamy ' of Linnaeus, through ' superfluous polygamy,' 

 to ' frustraneous ' on the one hand and ' necessary ' on the other, from either of which 

 monoecism and dioecism may arise, as in Carduus arvensis, Petasites, and Antennaria, 

 The variety, increasing complexity, and homology of the sexual arrangements, the 

 abundant links, and the abhorrence of the sexual union of nearly related cells are 

 the theme of the whole paper. 



Two Monstrosities o/ Matricaria iuodora. 

 By Professor Alexander Dickson, 31.D. 



1st. Where the florets of the capitulum were replaced by stalked secondary 

 capitula, some of which were in turn again similarly compound. That the secondary 

 capitula really resulted from transformed florets was interestingly shown by the 

 presence on the stalk of many of the outer secondary capitula of a ligulate corolla 

 with its base embracing the aSis. 



2nd. "Where many of the florets of the ray presented a narrow ligulate lip directed 

 inwards, these internal lips conniving more or less over the central disk. At first 

 sight this anomaly seemed to simulate the condition in Composite Labiatiflorffi ; 

 but so iiir as Dr. Dickson's examinations as yet went, it would appear that the 

 smaller lip Avas placed laterally to the normal line of non-union of the ligulate 

 corolla, and therefore was not a mesial structure compressed to the inner lip of the 

 floret in I>abiatiflorpe. 



