8 



u\ THE FERTILIZATION 



/,-, «„//* «/ r„ltiratlam of the pollen of Flcm Eoxburghli. 



A . rv extend eer < of cultivations was carried out both on the stigmatic 



urfaces o 



rewl ,taclcs ready for insect accecs, and in suitable flu.d media in sealed 



„„.«,„. In the case of the cultivations of the first kind the receptacles were 



Z fad transversely, p-Uen from mature anthers was smeared^ over the ^.gmatic 



BOi^Md'thc r rptacle was 'then placed in B moist chamber. In the other 



transversely, i>"iien irum " ""- - — • 



of the lower half, the upper half was again fitted on and pressed into 



f cultivation*, pollen-gnu na were immersed in a drop of fluid suspended on the 

 i idiT surface of the covcr-glass sealing a wax-cell. The solution which gave th 



remit* was a one per cent, one of cane sugar in water, and with this much 

 more constant and extensive evolution of pollen-tubes occurred than in any cultivations 

 on the sti -mafic surface. One great objection to the latter was found to lie in the 



freouearv with which growths of fungal mycelium made their appearance, the filaments 

 uviug a 1 vy mark d t ndency to adhere to the pollen-grains, and in many cases actually 

 i net rating and passing through them from one end to the other, so that they came 

 » be strung like beads on a thn-ad. Those grains which escaped in many cases germinated, 



emitting one or two tubes, but the growth always remained very limited. The tubes 

 wen v. a shortj and had a great tendency to become dilated at their extremities, after 



whi h no farther growth occurred (Plate IV, figs. 11, 12). In the case of the cover- 



pkm cultivations there was not so much liability to fungal intrusion, and the tubes grew 



much men freel; . Here they often attained a considerable length, the protoplasm gra- 



*1 lallv travelling outv ml.s, and frequently leaving the grain at a considerable distance 



hind as a mei empty shell. Ultimately, as in the stigmatic cultivations, a distal 



lilatation made its appearance, in which the protoplasm accumulated and from which it was 



finally di i -I. urged into the surrounding fluid (Plate IV, fig. 13). In some cases in stigmatic 



sultiv ations, ami more frequently in cover-glass ones, a few tubes showed a tendency to 

 brunch, but the resulting twigs always remained very short (I'late IV, fig. 13). 



\<>t. s <m the life-history of the fig-insect affecting Ficus Roxburghii 



in Calcutta. 



In the above heading the words "in Calcutta" have been deliberately introduced, 

 be- ause it remains uncertain whether the insect which is here related to the species is the 



same as that related to it in its normal habitat, and specific to it, or whether we have not 



to deal with a ca-^c of appropriation of an exotic host by an insect properly related to 

 f the figs native to the locality. There are some grounds for suspecting that this really 

 h the case. In the first place, it is somewhat hard to imagine how the insects, if specifically 



related to the tree, were originally introduced to Calcutta. They certainly could not 



been normally ,„t, educed by the plants first imported, as these were not at a stage to 



produce any fruit. It is, of course, possible that they may have been imported in receptacles 

 of F Rozburgkt, or accidentally along with other materials sent down to the Botanic Garden 



» Calcutta from the native habitat of the tree; but, as the life of the female insect appears 



to be very brief after emergence, and as the latter only occurs in detached receptacles when 



hey have been plucked when quite mature, and then very rapidly, there are difficulties 



the way of accepting this as a probable event. On the other hand, there are certain 



