4. Fortpflanzungslehre. 35 



73) Morill, C V., The Chromosomes in the Oögenesis, Fertiliza- 

 tion and Cleavage of Coreid Hemiptera. 



(Biological Bulletin 19,2. p. 79—126. 12 text-figs. 2 plates 1910.) 

 The studies on the relations of chromosomes with reference to sex have 

 usually involved the following assumptions: 



1, That in the formation of the polar bodies, the diploid chromosome- 

 groups of the female are reduced to haploid groups that are alike in the 

 mature eggs. 



2. Since the spermatozoa are of two sorts (in many insects at least) the 

 embryos produced would be correspondingly different, and this difference should 

 be appearant from a study of the embryonic nuclei. The author presents a 

 study of the chromosome groups in the oögenesis, fertilization and cleavage 

 in four species of coreid hemiptera in order to determine whether or not the 

 assumptions made in regard to the number and behavior of the chromosomes 

 in these stages are in accord whith the facts. 



The author's summary of results is as follows: 



'1. In Archimerus, Anasa and Protenor there is an odd or unpaired 

 chromosome in the spermatogonia which in Protenor is distinguishable by 

 its size. The oögonia contain in addition to this chromosome of the same size. 

 These observations are in agreement with those of Wilson, Montgomery 

 and of Lefevre and Mc Gill for the forms mentioned. 



2. The chromosomes in the reduced female groups (polar or oöcyte divi- 

 sions) show the same relative size differences as the corresponding pairs in 

 the oögonia (particularly well shown in Protenor). 



3. All the chromosomes divide in both polar divisions (proof decisive in 

 Archimerus, less complete in Anasa and Protenor). There are no pecu- 

 liar or 'lagging' chromosomes in either of these divisions. 



4. The female pronucleus contains a group of chromosomes similar to 

 that borne by a Spermatozoon having the 'accessory' or idiochromosome (di- 

 rectly proved in Archimerus). 



5. At fertilization the reduced groups from each pronucleus are separa- 

 tely distinguishable and the chromosomes show the same size relations as 

 those of the spermatocyte and oöcyte divisions. There are no nucleoli in 

 either pronucleus. 



6. In the cleavage and early blastoderm nuclei of Archimerus, Anasa, 

 Chelinidea and Protenor, the chromosomes are perfectly distinct and can 

 be counted as readily as those in the gonads. Two types of embryos are 

 found, one having an odd and the other an even number of chromosomes, 

 these numbers being respectively the same as occur in the spermatogonia and 

 oögonia. Accordingly it seems fair to conclude that the former are males, 

 the latter females, and it thus becames possible to distinguish the sex of the 

 embryo by counting its chromosomes. 



7. The idiochromosomes behave exactly like the other chromosomes, in 

 the oöcyte divisions, at fertilization and in the cleavage and early blastoderm 

 stages. They never show any resemblence to nucleoli and in Protenor they 

 can be identified in all stages with absolute certainty.' 



In conclusion on the author gives a summary of previous work on the 

 maturation and early development of the eggs of insects. Lillie (Chicago). 



74) Weyineersch, A. (Institut d 'Anatomie Warocque , Bruxelles), 



Mecanisme de l'avortement et de la restauration uterine apres 

 l'ablation des corps jaunes. 



(Bull, de la Societe R. des Sc. med. et nat. de Bruxelles 68,7. p. 189—201. 1910.) 



3* 



