SCIENTIFIC SUMMARY. 
197 
In fact, exogenous growth was found in vegetable organisms of very different 
affinities, and was not wholly characteristic of any one. It appeared to be 
a provision which was correlate with the general form of the whole mass of 
vegetative organs, and was forced upon the plant, in fact, as a necessary 
condition of its mechanical stability. For classificatory purposes the terms 
exogen and endogen were now almost universally abandoned, and Iiay’s 
designations, which were found quite valid, were used instead. 
The Passifloracece and their Modes of Fertilisation have been pretty 
thoroughly explored by Dr. Maxwell T. Masters, F.K.S., who has published, 
in the “ Transactions of the Linnaean Society,” a very fine memoir on the 
natural history of the whole order. He has also printed private copies of the 
memoir, from which we have the opportunity of quoting. The memoir should 
be fully read by all who are interested in the subject ; meanwhile, however,, 
we may refer to the author’s remarks on the subj ect of fertilisation of the 
flowers. It seems that in the young state the anthers are introrse and pressed 
up against the sides of the ovary and styles, the large stigmas of which, 
project beyond the anthers. When the anthers become sufficiently matured 
to allow of the emission of the pollen, they undergo a change of position : 
the filaments spread more or less horizontally, and the anthers become ex- 
trorse ; so that if the flower-stalk spread somewhat horizontally, as it does 
usually, or if it be erect, the pollen is likely to be shed on the corona, the 
styles at this stage being horizontal, with their stigmas quite out of reach 
of the pollen. In this manner the corona is often found dusted over with 
pollen 5 and in Passiflora cincinnata , Mast., and in other species it often, 
happens that the stamens are bent downwards to such an extent as to come 
into direct contact with the corona. The outermost rows of the corona,., 
then, appear to attract insects, the smaller threads proceeding from the- 
throat of the flower-tube catch the pollen, while the membranous or median- 
corona (operculum) shuts off the upper portion of the flower from the 
nectar-secreting portion at the base. In all cases the object seems to be to 
detain the insect in its passage to the nectar-secreting portions, and so to 
enable it the more surely to be dusted over with pollen. Now, when a bee 
visits an expanded flower, it is easy to see how the insect favours cross 
fertilisation. The insect alights on the rays of the corona ; and if there be 
pollen on them, some of it must naturally adhere to the hairs on the insect’s 
back. Moreover, if the insect be large, or the stamens, with their now ex- 
trorse anthers, be bent downwards, as they usually are at a late stage of the 
expansion of the flower, it is obvious that the back of the insect is very 
likely to come into contact (nay, does so, as he has frequently observed), 
and thus remove some of the pollen from them. In those cases where, from 
the pendulous position of the flower (P. quadrangularis , P. macrocarpa, &c.), 
the pollen cannot fall on the corona, which is now placed above the anthers, 
the pollen is removed by bees in the manner just indicated. When the 
pollen- carrying insects alight on the corona of another flower, it may so 
happen that the stigmas of that flower are so placed as to render them liable 
to come into contact with the insect, and to remove from its hairy thorax 
the pollen-grains with which it is bestrewn. The styles, which are erect 
all the time the anthers are introrse and so placed as to be liable to con- 
taminate the stigmas, gradually assume a horizontal or even a deflexed 
