MATURATION OF UNFERTILISED HGG IN TENTHREDINIDA. 571 
4, FrertitisED Eacs or N. RIBESII. 
I have not yet succeeded in working out thoroughly the 
development of the fertilised eges. The maturation divisions 
occur as in virgin eggs, and conjugation of the two inner 
nuclei takes place in the same way, but the subsequent 
development of the polar nuclei shows some slight differences. 
In many eggs from impregnated females the outer nucleus is 
found much further from the edge of the egg than in normal 
unfertilised eggs, and instead of rapidly degenerating it 
becomes resolved into a group of chromosomes, which persist 
for some time. ‘The two inner nuclei form a group of chromo- 
somes, but each of these commonly splits into two or more 
chromatin granules at a rather early stage, so that a large 
mass of small chromatin bodies is often found in the polar 
protoplasm. 
I have not been able to observe the conjugation of male 
and female pronuclei, and although spermatozoa have been 
found in some recently laid eggs, I have not been able to 
trace their subsequent development with certainty. There 
are indications that the spermatozoa develop into nuclei, 
which then disintegrate without ever conjugating with the 
egg nucleus, in which case the eggs of impregnated females 
would also be parthenogenetic. If this is the case, it would 
solve the difficulty which arises concerning the chromosome 
number, which is the same in somatic mitoses as in the 
maturation divisions. Since, however, the supply of material 
at present available is insufficient to determine the matter 
for the present, it must be left undecided. 
5. NEMATUS PAVIDUS AND N. LACTEUS.' 
Of these species N. pavidus is said by Cameron and 
others to yield only males from unfertilised eggs. With 
regard to N. lacteus I have obtained no information,! and 
1 See p. 563, footnote, | 
