﻿Contr. toward the Embryol. and Anat. of Pol. pallipes (Hymenopt.) 127 



anterior end, the egg tapering towards the posterior pole at the 

 extremity of which is the narrowest part. From this general shape 

 there are some deviations either in a relative lengthening or shor- 

 tening of the long axis, also in a suppression of the pointed end, 

 some few eggs shortening so much as to become nearly spherical. 

 The narrower posterior end is used for attachment in a cell of the 

 nest towards the opening of which the anterior end points. One 

 surface of the egg is concave or flattened, opposed to which is a 

 convex surface. There are often found irregularities in which either 

 the concavity or the convexity, or both, may be suppressed. The 

 convex surface becomes the ventral, the concave the dorsal aspect, 

 of the egg. This same orientation has been observed in Hymeno- 

 ptera by Kowalevsky (31) and Bütschli (9) for Apis, by Carriere 

 and Bürger (11) for Chalicodoma and by Ganin (16) for Formica. 



The eggs are attached, one in each cell, to that wall which is 

 nearest the center of the nest. In a few cells two eggs were found 

 which must have led, later, to the death of one or both of the larvae 

 which developed from these eggs. The point of attachment of the 

 egg is usually about two-thirds the depth of the cell. In the young 

 nests an egg is found in each cell, but as soon as these develop to 

 larvae the eggs are then found only in the youngest, outermost, cells 

 which have been added to the nest. The nest increases in size, the 

 eggs soon becoming larvae, the larvae, pupae, and we then find that 

 even the marginal row of cells is in part filled with pupae and eggs 

 can then be obtained from a few only of these outermost cells. The 

 development of the wasps in the central cells is finally completed 

 and when the mature wasps leave them they are used again, eggs 

 being found both in these central cells as well as some of those 

 comprising the marginal row. Both from what has been said, and 

 the fact that early development proceeds rapidly, the exceeding 

 difficulty of procuring many eggs in their earliest stages of deve- 

 lopment is appreciated. The occurrence of the wasps also varies 

 greatly in different years, and with this, the abundance or scarcity 

 of nests. 



The many eggs of Polistes sectioned by us have failed to show any 

 stages in the formation of the polar cells, the union of the pronuclei 

 or the earliest divisions of the cleavage nuclei. We begin our account 

 of the formation of the blastoderm after the earliest divisions of the 

 cleavage nuclei have already occurred. 



The earliest stage which we have found (Fig. 1), shows a small 



