EGGS AND LARVAE: BREEDING AND RKAIUXG. 311 



the shell must be exercised, as the young 1 larvae of many species 

 have the curious habit of whetting- their appetites for future 

 meals by turning- about, as soon as they have been hatched, and 

 eating the shell which they have just left. 



The eggs of insects are best mounted in the form of micro- 

 scopic slides in glycerine jelly contained in cells of appropri- 

 ate depth and diameter. It is well to mount several upon the 

 same slide, exhibiting the lateral as well as the terminal aspect 

 of the eg-gs. At the upper end of all insect eggs there are one 

 or more curious structures, known as micropyles (little doors), 

 through which the spermatozoa of the male find ingress and 

 they are fertilized. The peculiar, and often very beautiful, 

 features of this part of the egg are, in a w T ell-mounted specimen, 

 exposed to view r . In some cases it is advisable to slice off the 

 end of the eg-g with the micropyle and mount it microscopi- 

 cally. The best display of this curious structure is thus often 

 obtained. 



The slides should be kept in a cabinet arranged in shallow 

 trays. They should be accurately named, and have references 

 to a book into w r hich, from time to time, should be carefully 

 transcribed from the field-book the observations of the collector, 

 or his assistants and correspondents. Such a collection of in- 

 sect ova is not only valuable but intensely interesting. 



THE LARVA. By reference to the table of the classification of 

 the Arthropoda, given in Chapter XL., it will be observed that 

 the Insecta are broadly divisible into two groups, the Heterome- 

 tabola and the Metabola. The animals classified in the first 

 group do not underg-o metamorphosis in the development from 

 the egg to the perfect insect to the same extent and in the 

 same manner as the Metabola. In this respect the Peripatid< ;i, 

 the Myriapoda, and the various classes included under the 

 Acerata agree with them. The young mvriapod and the young- 

 spider are found immediately after they have emerged from the 

 egg- to present most of the features of the mature insect, and so 

 also the immature grasshopper and squash-bug resemble the 

 perfect insect in nearly everything but size and the absence of 

 fully developed wings. In preparing a suite of specimens of 

 these insects, designed to illustrate their life-history, the direc- 

 tions which are given for the preparation of the imago appl\ 



