Cacoecia and Euvanessa.
I had no intention of making an extended study of the spermatogenesis of the Lepidoptera, but was interested to see if anything corresponding to the heterochromosomes of other orders could be found. The material studied was the testes of the larvæ of Cacœcia cerasivorana and Euvanessa antiopa. The number of chromosomes is large, but the equatorial plates are diagrammatically clear. In both species 30 chromosomes are found in both first and second spermatocytes. In both, one chromosome is larger (figs. 290 and 293, x). In the growth stage (figs. 283, 284) there is a two-lobed body (or sometimes two separate spherical bodies) which seems to correspond in size to the larger pair of chromosomes in the first spermatocyte. In iron-hæmatoxylin preparations this pair is often obscured by parts of the spireme which are tangled around it. In safranin-gentian preparations it stains, not like a plasmosome, but red like the heterochromosomes, while the spireme is violet. The staining reaction at least suggests that this equal pair of chromosomes, which may be traced through the synizesis stage (fig. 280), synapsis stage (figs. 281, 282), growth stages (figs. 283, 284), and prophases (figs. 285-287), into the first spermatocyte spindle (figs. 288, 290), and on to the second spermatocyte (figs. 289, 291, 292), is an equal pair of heterochromosomes comparable to the equal pair of "idiochromosomes" found by Wilson in Nezara ('05). As the various stages are practically the same in Euvanessa antiopa, but somewhat clearer in Cacœcia, only one figure is given for Euvanessa—the equatorial plate of the first spermatocyte (fig. 293).
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.