112 CHARLES V. MOKRILL. 



ticus, finds a similar body in the growth period of the oocytes. 

 After tracing its history, he concludes however that it is com- 

 parable to a nucleolus and is not to be confused with a "hetero- 

 chromosome." Buchner's identification of the "accessory body" 

 as a chromosome thus appears very doubtful. 



Hymenoptera. Blochmann's ('89) observations on the matura- 

 tion of the fertilized and parthenogenetic egg of the bee were con- 

 cerned chiefly with the number of polar bodies formed in the two 

 sorts of eggs. Though the polar spindles were figured the exact 

 number of chromosomes was not determined. Henking ('92) 

 found the haploid number of chromosomes to be 10 in the polar 

 spindles of Lasius niger and the diploid number in the cleavage 

 spindles, 20. In the unfertilized egg of Rhodites rosa he found 9 

 chromosomes in the polar spindles. In the cleavage nuclei the 

 number was 18-20, i. e., the number of chromosomes in the female 

 pronucleus had been doubled. Petrunkewitsch ('01) working on 

 the fertilized and parthenogenetic eggs of the bee, found that 

 the first polar division was equational, the number of chromo- 

 somes being 16. In the second division there occurred in both 

 sorts of eggs, a reduction of the chromosome-number to about 

 half, i. e., from 16 to 8. In the parthenogenetic (drone-) eggi 

 the female pronucleus contained at first 8, but later 16 chromo- 

 somes, the latter being produced by a doubling of the haploid 

 group, so that in the equatorial plate of the first cleavage spindle 

 the diploid number, 16, again appeared. In later cleavages there 

 was a progressive doubling of the chromosome-number, producing 

 multiple groups of 32 and 64. Silvestri ('06 and '08) has de- 

 scribed in detail the maturation, fertilization and cleavage of 

 several species of parasitic hymenoptera (Litomastix, Encyrtus, 

 Oophthora, Ageniaspis}. However, since his results do not in- 

 clude the determination of the exact number of chromosomes in 

 the early stages, it will be unnecessary to review them here. 

 Doncaster's ('07) results on Nematns ribesii (Tenthredinidae) are 

 quite anomalous and difficult to interpret. He finds that there 

 are two types of maturation in tin- female. In some egg^ there 

 is no reduction of chromosomes, the female pronucleus receiving 

 the diploid number, 8. In others typical reduction occurs, the 

 egg nucleus receiving in all probability the haploid number, 4. 



