SUMMARY OF RESULTS.
(1) An unequal pair of heterochromosomes has been found by the author in 19 species of Coleoptera belonging to 8 families:
| Family. | Species. | ||
| I. | Buprestidæ | Two spruce-borers, species not determined. | |
| { | 1. Chlænius æstivus. | ||
| II. | Carabidæ | { | 2. Chlænius pennsylvanicus. |
| { | 3. Galerita bicolor. | ||
| { | 1. Blepharida rhois. | ||
| { | 2. Chelymorpha argus. | ||
| { | 3. Coptocycla aurichalcea. | ||
| III. | Chrysomelidæ | { | 4. Coptocycla guttata. |
| { | 5. Doryphora decemlineata. | ||
| { | 6. Odontota dorsalis. | ||
| { | 7. Trirhabda virgata. | ||
| { | 8. Trirhabda canadense. | ||
| IV. | Cicindelidæ | Cicindela primeriana. | |
| V. | Coccinellidæ | { | Adalia bipunctata. |
| { | Epilachna borealis. | ||
| VI. | Scarabæidæ | Euphoria inda. | |
| VII. | Silphidæ | Silpha americana. | |
| VIII. | Tenebrionidæ | 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,[A] belonging to 3 families:
| Family. | Species. |
| I. Carabidæ | Anomoglossus emarginatus. |
| II. Elateridæ | Two Elaters; species not determined. |
| III. Lampyridæ | 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 spread out in the nuclear space, and, with the exception of the heterochromosomes, unite to form a continuous spireme.
(5) In several of the species of Coleoptera and in Aphrophora, it has been shown that a body staining like chromatin develops in the spermatids, increasing in size for a time, then breaking up into granules and disappearing. This body evidently has no relation to the heterochromosomes, as it is the same for all of the spermatids. Its staining qualities suggest that it may be material derived from the chromosomes. It is finally dissolved in the karyolymph.
(6) In iron-hæmatoxylin preparations the heterochromosomes of the Coleoptera vary greatly in their staining properties during mitosis. In some species they stain exactly like the ordinary chromosomes, in others the larger one of the unequal pair holds the stain more tenaciously than the others and also than its smaller mate, and this is true in several cases where the heterochromosome is smaller than the other chromosomes, which destain more readily. The odd chromosome of the Elaters stains less deeply than the others in the first spermatocyte. In the growth stage they stain more deeply, as a rule, than the spireme, with iron-hæmatoxylin or thionin, stain red with safranin-gentian and green with Auerbach's methyl green-fuchsin combination.
(7) Aphrophora quadrangularis agrees with the Anasa group of Hemiptera heteroptera in having a pair of m-chromosomes and an odd chromosome in the spermatocytes, but differs from many of that group in that the odd chromosome divides in the second mitosis instead of the first. It also differs from other known forms in exhibiting heterochromosomes in certain stages of the oöcytes.
(8) The two species of Lepidoptera examined have an equal pair of heterochromosomes.