158 f-J">.^. 



On April 14th some eggs were to be seen, laid on the upper side of 

 the most exjmnded lower folioles of the fern. They lay along the hollow 

 of the central mid-rib of the foliole. They seem to lie on the surface with 

 the long axis parallel with the mid-rib. They are bright orange-yellow, 

 ovoid ; length 0'81 mm., width 0"4o mm. ; one end is a little raised from 

 the leaf, the other end nearer it. They suggest that one must handle 

 CHi'efully or they will be shaken off. On examination it appeared that 

 they were far fi'om loose. They were, in fact, most firmly attached to 

 tlie leaf. An}' unconsidered attempt to remove one required much force, 

 and resulted in tearing the eggs off, with rupture at its junction with 

 the leaf. The slight incline of the egg was found to be constant, and 

 not a result of the eggs being laid as it were anyhow, as seemed at fii"st 

 probable. A closer examination showed that the egg was held not l)y 

 • any gum or cement, but by a small portion of it being gi-ipped in a short 

 gutter in the middle line of the leaflet. Freeing the egg by splitting 

 the leaf was difficult, but was successfull}^ achieved in several instances. 

 It seemed that the egg-shell and leaf in the gutter were organically 

 connected. 



Where the fern kept alive and green, the eggs remained plump and 

 hatched; if the fern at all failed, the eggs shrank a little and died: so 

 that it seemed certain that the egg obtained from the leaf, if not 

 nourishment also, at least fluids to meet its loss by evaporation. 



The removed egg chowed a raised ridge drawn out of the gutter in 

 the leaf. This w^as so short and small as to have raised no suspicion, 

 until it was so demonstrated, that the egg was otherwise than siin])ly 

 egg-shaped. The gutter had a slight raised margin on each side, possiblv 

 merely the result of being pushed aside to make room for the egg. 

 The length of the portion of the gutter holding the egg is about 0-28 mm., 

 but the appearance of the leaf suggests that the actual incision is rather 

 longer — perhaps 0-38 nim. I could not measure the length of the Hap of 

 egg-shell buried in the leaf, but from the eggs I succeeded in separating, 

 in which the flap did not retain its form, I took it to be about 0"12 to 

 O-ll mm. 



The incision in the leaf is no doubt made by the sawfly in the usual 

 way, and the egg begins to be laid whilst the saw is fully imbedded. The 

 egg, as we know to be the case in so many (nearly all?) sawflies, is no 

 doubt almost fluid and the shell in a thoroughly plastic condition. So soon 

 as a portion of the egg reaches the bottom of the gutter, the saws no 

 doubt begin to be withdrawn ; but before the rest of the egg leaves the 

 ovipositoi', the fern-tissue closes on the imbedded egg-shell and grips it 

 tii'inly, thus almost organic conneetion bt'twceu the two soon taking place. 



