III. Chrysomelidae 



SUMMARY OF RESULTS. 49 



SUMMARY OF RESULTS. 



(i) An unequal pair of heterochromosomes lias been found by the 

 author in 19 species of Coleoptera belonging to 8 families : 



Family. Specibs. 



I. Buprestidje Two spruce-borers, species not determined. 



SI. ChlcEnius cEStivus. 

 2. Chlcenius fennsylvanicus. 

 3. Galerita bicolor. 

 { I. Blefharida rhois. 



2. Chelymovpha argus. 



3. Coftocycla aurichalcea. 



4. Coftocycla guttata. 



5. Doryfhora decemlineata. 



6. Odontota dorsalis. 



7. Trirhabda virgata. 



8. Trirhabda canadense, 

 IV. Cicindelidae Cicindela ■primeriana. 



V. CoccinellidEe | AdaLia bitunctata. 



(. Efilachna boreatis. 



VI. Scarabaeidas Euphoria inda. 



VII. Silphidae Silpha americana. 



VIII. Tenebrionidae Tenebrio molitor. 



(2) An odd chromosome, which behaves during the growth stage of 

 the first spermatocytes like the " accessory " of the Orthoptera, has 

 been found in 4 species of Coleoptera,* belonging to 3 families: 



Family. Species. 



I. Carabidse Anomoglossus emarginatus. 



II. Elateridae Two Elaters ; species not determined. 



III. Lampyridae Ellychnia corrusca. 



(3) In most of the species of Coleoptera examined, the unequal pair 

 or the odd chromosome remains condensed during the growth period 

 of the first spermatocyte, like the ' ' accessory ' ' of the Orthoptera and 

 the various heterochromosomes of the Hemiptera. 



(4) Several of these species of Coleoptera have a synizesis stage in 

 which the spermatogonial number of short loops is massed at one side 

 of the nucleus. This is followed by a synapsis stage in which the 

 loops straighten and unite in pairs, forming longer loops which soon 



*AuG. 20, 1906. — Since this paper was prepared, 19 other species of Coleoptera 

 have been studied. Of these, 17 have an unequal pair of heterochromosomes in the 

 spermatocytes. Six belong to the Chrysomelidae, making 14 of that family that have 

 been examined. Representatives of 4 new families — Melandryidas, Lamiinse, Mel- 

 oidae, Cerambycinae — have been studied. In only two species, — i Elater and i 

 Lampyrid — has the odd chromosome been found in place of the unequal pair. No 

 species of Coleoptera has yet been examined in which one or the other of these two 

 types of heterochromosomes does not occur in the spermatocytes. Of the 42 species 

 of Coleoptera whose germ cells have been studied, 85.7 per cent are characterized by 

 the presence of an unequal pair of heterochromosomes in the male germ cells, 14.3 

 per cent by the presence of an odd chromosome. 



