Objects for the Microscope. 113 



and I doubt not there are volumes, countless and full of 

 eternal wisdom, laid up in store for those who delight in 

 the study of God's works. 



We can now return to the slide before us. The colour 

 of the Saw-fly is necessarily lost in preparing it transpa- 

 rently for our examination ; but it was a bright and beau- 

 tiful fly, yellow, or scarlet, or light green dotted with black. 

 They provide for their young thus. I had the pleasure of 

 watching the motherly care of the Saw-fly of the rose (Ten- 

 thredo roses) last summer. 



A busy little fly with black thorax and yellow abdomen 

 was at work upon a rose-tree so intently that she did not 

 stir when I drew near to see what she was about. She bent 

 her abdomen as you see here, and had protruded a pair of 

 cutters such as these. They are, in fact, finely-toothed saws 

 with about eighteen teeth each, and run backwards and 

 forwards in a grooved back-piece, which fits on each like a 

 carpenter's tennon saw. They worked alternately, and pre- 

 sently she changed her position : she had been cutting down 

 deep,"uow she wanted to make a long groove, and straight- 

 ened her body, sawing quite fast and steadily, making a 

 furrow about half an inch long. Then she paused, and a 

 little greenish egg was laid on one side, another on the 

 opposite side, all along until a double row had been depo- 

 sited of about twenty eggs ; she then gave out a frothy glue 

 which seemed to fix and protect them, drew in her ovipositor, 

 and flew off to a neighbouring tree, where I took her for 

 examination of the saws. The little eggs I looked at with 

 a pocket lens, and found they were separated up the middle 

 of the groove by a fibre left on purpose. From day to day 

 I watched them, and they increased in size, which is differ- 

 ent from all other eggs ; the edges of the furrow became 

 black and swollen, but did not close, and about ten days 

 after I found all the little eggs empty, and several tiny green 

 and black-dotted caterpillars wandering about, very like 

 true caterpillars, which they are not, as may always be 

 known by counting their feet, eighteen or twenty, whereas 

 the larvse of butterflies and moths, which are real cater- 

 pillars, have only from ten to sixteen, and never more. 



